全文获取类型
收费全文 | 331251篇 |
免费 | 15384篇 |
国内免费 | 861篇 |
出版年
2021年 | 1786篇 |
2018年 | 15822篇 |
2017年 | 14722篇 |
2016年 | 11766篇 |
2015年 | 3850篇 |
2014年 | 4734篇 |
2013年 | 6632篇 |
2012年 | 12184篇 |
2011年 | 22291篇 |
2010年 | 18934篇 |
2009年 | 14438篇 |
2008年 | 18472篇 |
2007年 | 20842篇 |
2006年 | 7502篇 |
2005年 | 7702篇 |
2004年 | 8114篇 |
2003年 | 8115篇 |
2002年 | 7817篇 |
2001年 | 9627篇 |
2000年 | 9280篇 |
1999年 | 7041篇 |
1998年 | 2142篇 |
1997年 | 1978篇 |
1996年 | 1853篇 |
1992年 | 5515篇 |
1991年 | 5763篇 |
1990年 | 5672篇 |
1989年 | 5653篇 |
1988年 | 5249篇 |
1987年 | 4913篇 |
1986年 | 4461篇 |
1985年 | 4698篇 |
1984年 | 3743篇 |
1983年 | 3071篇 |
1982年 | 2041篇 |
1981年 | 1742篇 |
1980年 | 1736篇 |
1979年 | 3360篇 |
1978年 | 2597篇 |
1977年 | 2406篇 |
1976年 | 2345篇 |
1975年 | 2855篇 |
1974年 | 3140篇 |
1973年 | 3101篇 |
1972年 | 3440篇 |
1971年 | 3252篇 |
1970年 | 2230篇 |
1969年 | 2168篇 |
1968年 | 2037篇 |
1967年 | 1800篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
941.
Eriocaulon raipurense (Eriocaulaceae) is described and illustrated as a new species from Madhya Pradesh, India. The species is closely allied to E. hamiltonianum but differs in the size and apex of involucral bancts, white-pilose nature of floral bracts and colour of female petals. 相似文献
942.
943.
944.
Shallow-water vegetated estuarine habitats, notably seagrass, mangrove and saltmarsh, are known to be important habitats for
many species of small or juvenile fish in temperate Australia. However, the movement of fish between these habitats is poorly
understood, and yet critical to the management of the estuarine fisheries resource. We installed a series of buoyant pop nets
in adjacent stands of seagrass, mangrove and saltmarsh in order to determine how relative abundance of fishes varied through
lunar cycles. Nets were released in all habitats at the peak of the monthly spring tide for 12 months, and in the seagrass
habitat at the peak of the neap tide also. The assemblage of fish in each habitat differed during the spring tides. The seagrass
assemblage differed between spring and neap tide, with the neap tide assemblage showing greater abundances of fish, particularly
those species which visited the adjacent habitats when inundated during spring tides. The result supports the hypothesis that
fish move from the seagrass to the adjacent mangrove and saltmarsh during spring tides, taking advantage of high abundances
of zooplankton, and use seagrass as a refuge during lower tides. The restoration and preservation of mangrove and saltmarsh
utility as fish habitat may in some situations be linked to the proximity of available seagrass. 相似文献
945.
Characterization of transverse tubule membrane proteins: tentative identification of the Mg-ATPase 总被引:1,自引:0,他引:1
V R Okamoto M P Moulton E M Runte C D Kent H G Lebherz A S Dahms R A Sabbadini 《Archives of biochemistry and biophysics》1985,237(1):43-54
Vesiculated fragments of chicken skeletal muscle transverse tubule (TT) membranes were analyzed for their content of loosely associated and integral membrane proteins. Of particular interest was the identification of the magnesium-stimulated ATPase (Mg-ATPase), which is characteristically located in native isolated TT vesicles of chicken skeletal muscle [R. A. Sabbadini and V. R. Okamoto (1983) Arch. Biochem. Biophys. 223, 107-119]. A number of the proteins found in vesicular TT preparations were found to be extractable by a mild Triton-X100 treatment and were identified as aldolase, enolase, creatine kinase, glyceraldehyde-3-phosphate dehydrogenase, lactate dehydrogenase, and pyruvate kinase. Approximately 60% of TT-associated protein was extracted with Triton, resulting in a twofold enrichment of the Mg-ATPase. Concommitantly, one core integral membrane protein possessing a Mr of 102,000 was enriched, suggesting that it is responsible for the Mg-ATPase activity present in chicken skeletal muscle TT membranes. 相似文献
946.
947.
Histological and electron microscopy findings suggesting the effect of monochromatic coherent polarized red light on zymosan arthritis in rats are presented. The data obtained have confirmed that treatment of inflamed joints with laser rays exerts an evident therapeutic effect which is determined by activated function of macrophages and fibroblasts of the synovial membrane, resulting in a more rapid change of inflammation phases. Analysis of the cases where the rats were treated with ordinary red light has revealed no essential differences in the joints of the control and irradiated groups. 相似文献
948.
B S Kasavina Iu F Ma?chuk T V Ukhina 《Biulleten' eksperimental'no? biologii i meditsiny》1983,95(3):44-45
Activity of phosphodiesterases disintegrating cAMP and cGMP in the cornea, sclera and ciliary body was investigated in health and in different stages of experimental herpetic keratitis. The problems concerning the role of the cyclase system in the pathogenesis of herpetic keratitis and the possibility of applying some of the drugs to the disease treatment are discussed. 相似文献
949.
L A Novikova S M Dracheva A S Zubatov V N Luzikov 《Biokhimii?a (Moscow, Russia)》1982,47(8):1401-1408
The proteins of submitochondrial particles solubilized with 0.1% Triton X-100 were separated by polyacrylamide gel electrophoresis. Hydrolysis of several proteinase substrates was registered directly in the gel after completion of electrophoresis. According to the data obtained the inner mitochondrial membrane contains one or two enzymes which catalyze hydrolysis of cytochrome c as well as one or two enzymes splitting synthetic substrate of trypsin-like proteinases, e. g. N-alpha-benzoyl-L-arginine-p-nitroanilide (BAPA) and N-alpha-benzoyl-L-arginine-beta-naphthylamide (BANA). Submitochondrial particles were shown to catalyze hydrolysis of 3H-labelled cytochrome c. This activity is suppressed by the same inhibitors as the hydrolysis of mitochondrial translation products, i. e. phenyl-methylsulfonylfluoride, p-chloromercuribenzosulfonate, leupeptin and antipain. Presumably these two processes are catalyzed by the same enzyme localized in the inner mitochondrial membrane. Physiological functions of BAPA- and BANA-hydrolyzing enzyme(s) are still unclear. 相似文献
950.
The lipid dependence of pyrophosphatase activity was studied by treatment of liver and hepatoma microsomes with phospholipase C from Cl. perfringens and B. cereus and a subsequent incorporation of various classes of phospholipids into the delipidated microsomes. Phospholipase C hydrolysis sharply lowers the pyrophosphatase activity of liver and hepatoma microsomes. The enzyme activity is restored after introduction of phospholipids into delipidated liver microsomes, the maximal effect being achieved on incorporation of phosphatidylcholine. All the phospholipids tested exerted the same reactivation effects on the delipidated microsomes of hepatoma. However, a more complete delipidation of hepatoma microsomes by phospholipase C hydrolysis and a subsequent organic solvent extraction revealed a specific dependence of the enzyme activity on phosphatidylserine. 相似文献