Comparative analysis of domestic and foreign coal mine safety supervision modes based on knowledge map.

In order to grasp the research status and hot frontier of coal mine safety supervision mode in the world in the past 40 years, this paper takes the relevant literature in the field of "coal mine safety" and "supervision" included in the core collection of Web of Science (WOS) and the core journals of CNKI as the data source; based on the methods of statistical analysis and bibliometrics, the visualization analysis software CiteSpace is used to draw the map of scientific knowledge. Through the visualization analysis of the main research institutions, countries, and authors in this field, the main research forces and the distribution of researchers in this field are described. Through the visualization analysis of key words and research clustering, the research hotspots and future development trends in this field are described. The results show that the research hotspots of coal mine safety supervision mode at home and abroad are roughly the same, and the researchers and institutions in this field still need to further carry out cross regional and cross departmental wide area cooperation.

(3 + 2)-Annulation of p-Quinamine and Aryne: A Strategy To Construct the Multisubstituted Hydrocarbazoles.

A strategy for the synthesis of multisubstituted hydrocarbazoles has been developed through (3 + 2)-annulation of p-quinamines and arynes. In this way, new analogs of hydrocarbazoles with quaternary carbon center can be synthesized in satisfactory yield under mild conditions. Furthermore, this (3 + 2)-annulation can be easily scaled-up, and the products can be modified through simple transformation.

Protecting-Group-Free Total Synthesis of (-)-Lycopodine via Phosphoric Acid Promoted Alkyne Aza-Prins Cyclization.

A protecting-group-free route for the total synthesis of (-)-lycopodine was demonstrated in only 8 steps from Wade's fawcettimine enone (12 steps from commercial availiable (R)-(+)-pulegone). The key core of this alkaloid was constructed through a phosphoric acid promoted and highly stereocontrolled alkyne aza-Prins cyclization reaction, synchronously establishing the bridged B-ring and the C13 quaternary stereocenter. Importantly, the synthesis further features a new efficient approach for the preparation of other lycopodine-type alkaloids.

Asymmetric Total Synthesis of (-)-Lycospidine A.

The first asymmetric total synthesis of the structurally unique Lycopodium alkaloid (-)-lycospidine A, containing an unprecedented five-membered ring, has been accomplished in only 10 steps with 21.6% overall yield from the known conveniently available sulfoxide. This protecting-group-free short synthesis relied on the use of a key amidation/aza-Prins domino cyclization reaction to rapidly construct the tricyclic skeleton and two continuous stereocenters (one of which is a bridged quaternary stereocenter). An intramolecular aldol condensation was successfully utilized to establish the unique five-membered ring, and a late-stage oxidation inspired by biosynthesis pathway was adopted to synthesize the diosphenol ring of (-)-lycospidine A.

Visible-Light-Promoted Dual C-C Bond Formations of Alkynoates via a Domino Radical Addition/Cyclization Reaction: A Synthesis of Coumarins.

A visible-light-promoted, mild, and direct difunctionalization of alkynoates has been accomplished. This procedure provides a new strategy toward synthesis of the coumarin core structure by photoredox-mediated oxidation to generate the α-oxo radical, which supervenes a domino radical addition/cyclization reaction in moderate to good yields with high regioselectivity at ambient temperature.

Bioinspired Total Syntheses of Isospongian-type Diterpenoids (-)-Kravanhins†A and C.

The first bioinspired total syntheses of (-) kravanhins A and C were accomplished from a labdane diterpenoid derivative. The key reactions involve a photooxidation and a one-pot sequential aldol cyclization and lactonization, which provide a new plausible biosynthetic pathway for the kravanhins and other symbiotic members.

Short and Scalable Total Synthesis of Myrioneuron Alkaloids (±)-α,ß-Myrifabral A and B.

The first total synthesis of the Myrioneuron alkaloids (±)-α,ß-myrifabral A and B has been accomplished in only four steps from conveniently available starting materials. This short synthesis relied on the use of a key tandem Mannich/amidation reaction to rapidly construct the core framework and two carbon stereocenters. The synthetic route allows for large scale preparation of these promising natural products against the hepatitis C virus (HCV).

Asymmetric Total Synthesis of (-)-Kravanhin†B.

The first asymmetric total synthesis of kravanhin B has been accomplished with a linear reaction sequence of 13 steps starting from (R)-(-)-carvone. The synthesis features an intramolecular aldol cyclization to construct the desired cis-fused decalin skeleton and an acid-catalyzed dehydration and olefin isomerization to install the γ-butenolide ring.

Biomimetic Total Syntheses of (+)-Dihydrolyfoline and (-)-5-epi-Dihydrolyfoline.

The first asymmetric total syntheses of (+)-dihydrolyfoline and (-)-5-epi-dihydrolyfoline have been achieved in five and six steps with 4.6% and 14% overall yields, respectively, in which the chiral biaryl axes were constructed in a highly regioselective and stereoselective manner via a biogenetic enzymatic oxidative couplings of phenols, and the requisite quinolizidinone cores were prepared by an enzymatic Mannich reaction.

[Effects of acupuncture plus acupoint sticking on bone mass density and pain in the patient of primary osteoporosis].

OBJECTIVE: To observe effects of acupuncture plus acupoint sticking of Migudan on bone mass density (BMD) and pain in the patient of primary osteoporosis. METHODS: By computer random number generating method, the patients were randomly divided into a treatment group treated with acupuncture plus acupoint sticking of Migudan, and a control group treated with Gaitianli, 48 cases in each group. Changes of their BMD and cumulative scores of pain after treatment were investigated. RESULTS: Acupuncture plus acupoint sticking of Migudan could relieve cumulative score of bone pain in the patient of primary osteoporosis as compared with the control group (P 0.01), with 95% CI= 4.05 to approximately 4. 31 points; acupuncture plus acupoint sticking of Migudan could increase significantly BMD in the patients as compared with the control group (P < 0.05), L2 to approximately L4 BMD 95% CI = 0.029 to approximately 0.073 g/cm2, the neck of femur BMD 95% CI = 0.013 to approximately 0.047 g/cm2. CONCLUSION: Acupuncture plus acupoint sticking of Migudan has definite therapeutic effect on primary osteoporosis.