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21.
22.
A U Siddiqui W K Wilson S Swaminathan G J Schroepfer 《Chemistry and physics of lipids》1992,63(1-2):115-129
Protected forms of dehydroepiandrosterone, delta 5 cholenic acid, (25R)-26-hydroxycholesterol and diosgenin were converted to the corresponding delta 5,7 dienes by successive treatment with 1,3-dibromo-5,5-dimethylhydantoin (dibromantin), tetrabutylammonium bromide and tetrabutylammonium fluoride. The crude products, which contained the delta 5,7 species contaminated by minor amounts of the delta 5 and delta 4,6 steroids, were purified by silica gel-AgNO3 chromatography to give the following steroids in approximately 99% purity and at least 50% yield: 3 beta-acetoxyandrosta-5,7-dien-17-one, methyl 3 beta-acetoxychola-5,7-dien-24-oate, (25R)-3 beta,26-diacetoxycholesta-5,7-diene and (25R)-3 beta-acetoxyspirosta-5,7-diene. Analogous treatment of acetate derivatives of pregnenolone and stigmasterol gave 3 beta-acetoxypregna-5,7-dien-20-one and 3 beta-acetoxystigmasta-5,7,22-triene in approximately 50% yield but of lower purity. Full 1H and 13C NMR assignments are given for seven delta 5,7 steroid acetates and the corresponding delta 5 starting materials. Coupling constants for rings A, B and C of delta 5,7 steroids are presented and stereochemical assignments have been made for the following 1H NMR signals: the C-11 protons of delta 5,7 steroids, the C-16 protons of sterols and bile acids, the C-22 and C-23 protons of bile acid esters and the C-28 protons of stigmasterol derivatives. 相似文献
23.
F Dyda W Furey S Swaminathan M Sax B Farrenkopf F Jordan 《The Journal of biological chemistry》1990,265(29):17413-17415
Single crystals of the thiamin diphosphate (the vitamin B1 coenzyme)-dependent enzyme pyruvate decarboxylase (EC 4.1.1.1) from brewers' yeast have been grown using polyethylene glycol as a precipitating agent. Crystals of the homotetrameric version alpha 4 of the holoenzyme are triclinic, space group P1, with cell constants a = 81.0, b = 82.4, c = 116.6 A, alpha = 69.5 beta = 72.6, gamma = 62.4 degrees. The crystals are reasonably stable in a rotating anode x-ray beam and diffract to at least 2.5 A resolution. The Vm value of 2.55 A/dalton is consistent with a unit cell containing four subunits with mass of approximately 60 kDa each. Rotation function results with native data indicate strong non-crystallographic 222 symmetry relating the four identical subunits, thus density averaging methods are likely to play a role in the structure determination. 相似文献
24.
Guinea pig lymph node lymphocytes and human peripheral blood lymphocytes when stimulated by specific antigen or mitogen will release factors that affect in vitro macrophage migration. Migration inhibition factor production appears to be under the control of suppressor cells which are T lymphocytes. When suppressor cells are generated by stimulation with Con A for 4 days, migration stimulation factor (M.St.F.) activity is found. In other situations where M.St.F. is found this is thought to be due to increased suppressor cell activity. For example, young adults produce this lymphokine when stimulated with Con A, whereas aged individuals produce MIF. Concanavalin A appears to be the mitogen of choice for M.St.F. production, and phytohemagglutinin for MIF production. The release of this putative factor M.St.F. from suppressor T cells helps to explain some of the difficulties that have existed in studies of macrophage migration inhibition. 相似文献
25.
The crystal and molecular structure of 6-deoxy-l-sorbose have been determined by the application of multisolution methods and refined to an R-index of 0.063 for 560 reflections, using three-dimensional intensity data collected on a Picker automatic diffractometer. The compound crystallizes in the space group P212121 with unit-cell dimensions a = 18.470 (10), b = 7.636 (10), and c = 5.371 (8) Å; Z = 4. The molecule occurs as the α-furanose form, which is also the preponderant tautomer in solution. The puckering of the furanoid ring is C-3′-exo-C-4′-endo (3T4) [equivalent to C-2′-exo-C-3′-endo (2T3) in the numbering for d-ribose], with P and τm angles of -6.5 and 42.7° respectively. Conformational analysis of the known ketofuranosides shows that the 3T4 (2T3 in d-ribose numbering) puckering mode, which is typical of α-nucleosides, is favored, in contrast to the favored 3T2 or 2T3 puckering mode for the β-d-ribonucleosides and β-d-arabinonucleosides. The conformational differences among furanoid rings are mainly influenced by the configuration at the anomeric carbon atom. The favored orientation about the C-2′-C-1′ bond (O-5′-C-2′-C-1′-O-1′)of the ketofuranosidesis — gauche. All four hydroxyl groups are involved in donor-acceptor hydrogen bonding, and O-4′-8 appears to be involved in a bifurcated hydrogen bond to O-2′ and O-3′ of neighboring molecules. 相似文献
26.
B M Arnold M Kuttner R Swaminathan A D Care A J Hitchman J E Harrison T M Murray 《Canadian journal of physiology and pharmacology》1975,53(6):1129-1134
We have developed a radioimmunoassay for porcine intestinal calcium-binding protein (CaBP) and have used it to detect CaBP in pig plasma. Plasma CaBP is identical to intestinal CaBP on the basis of immunological activity, molecular size, and molecular charge properties. The plasma CaBP concentration was greater in the portal blood than in mixed venous blood, suggesting that blood CaBP originates in the gut. Two of four 15-week-old littermate pigs were placed on a low calcium diet (0.15% calcium, 0.65% phosphorus) and two on a control diet (0.65% calcium, 0.65% phosphorus). After 2 weeks, the entire small intestine was removed and divided into nine 1.8-m segments. CaBP was assayed in both plasma and intestinal mucosa. When the two pigs on a low calcium diet were compared with two control pigs, there was a general increase in immunoreactive CaBP in both plasma and intestinal mucosa. However, there was no increment in immunoreactive CaBP in the first 1.8-m segment of small intestine. Seventy-one percent of the increment in CaBP occurred distal to the first two segments. The largest fractional low calcium diet effect occurred in the ileum. The mean CaBP concentration for the total small intestine increased by a factor of 1.9. The plasma CaBP concentration increased by a factor of 2.6. In these pigs, plasma CaBP was a more reliable indicator of change in CaBP status than was the measurement in the proximal gut segment which contained the duodenum. The assay of CaBP in blood is convenient and may obviate the sampling errors inherent in intestinal biopsy. 相似文献
27.
28.
R Swaminathan 《Clinical physiology and biochemistry》1985,3(4):204-207
Digoxin administration to 6 volunteers for 7 days was associated with a small but significant decrease in total body (90 mmol) and erythrocyte potassium (4.8 mmol/kg cells). 相似文献
29.
30.
Nicholas Murgolo Alex G. Therien Bonnie Howell Daniel Klein Kenneth Koeplinger Linda A. Lieberman Gregory C. Adam Jessica Flynn Philip McKenna Gokul Swaminathan Daria J. Hazuda David B. Olsen 《PLoS pathogens》2021,17(2)
Since the initial report of the novel Coronavirus Disease 2019 (COVID-19) emanating from Wuhan, China, Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has spread globally. While the effects of SARS-CoV-2 infection are not completely understood, there appears to be a wide spectrum of disease ranging from mild symptoms to severe respiratory distress, hospitalization, and mortality. There are no Food and Drug Administration (FDA)-approved treatments for COVID-19 aside from remdesivir; early efforts to identify efficacious therapeutics for COVID-19 have mainly focused on drug repurposing screens to identify compounds with antiviral activity against SARS-CoV-2 in cellular infection systems. These screens have yielded intriguing hits, but the use of nonhuman immortalized cell lines derived from non-pulmonary or gastrointestinal origins poses any number of questions in predicting the physiological and pathological relevance of these potential interventions. While our knowledge of this novel virus continues to evolve, our current understanding of the key molecular and cellular interactions involved in SARS-CoV-2 infection is discussed in order to provide a framework for developing the most appropriate in vitro toolbox to support current and future drug discovery efforts. 相似文献