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11.
大狼毒三萜类化学成分的研究 总被引:3,自引:0,他引:3
自大戟科(Euphorbiaceae)植物大狼毒(Euphorbia nematocypha Hand—Mazz)根的乙醇提取物的苯溶解部分,经20%AgNO3硅胶层析,分离得到七个三萜类成分。根据光谱(IR,EIMS,1H—NMR和13C—NMR)和化学方法,确定其中一个化合物为新化合物,命名为大狼毒醇(nematocyphol,Ⅳa),其它化合物为已知物:印度荆芥醇乙酸酯(nepehinol acetate Ⅰ),日尔曼醇乙酸酯(germanicol acetate Ⅱ),大戟醇(euphol,Ⅲ),蒲公英醇(taraxasterol,Ⅴa),24-亚甲基环阿尔廷醇(24-methylenecycloartanol,Ⅴa)和印度荆芥醇(nepehinol,Ⅶa)。这些化合物均为首次从大狼毒中得到。 相似文献
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Milk and orange juice (OJ) fortified with calcium-citrate-malate (CCM; calcium-citrate-malate salt is a coined term to describe a trademarked calcium delivery system found only in Citrus Hill Plus Calcium) were evaluated for their potential to alter urine chemistries and crystallization during the course of an eleven week, crossover study. Six male and six female, non-stone-forming, idiopathic hypercalciuric adults consumed 600 mg per day as beverage calcium for four consecutive weeks. The results show that both milk and CCM-fortified OJ (CCM-OJ) were well tolerated by male and female hypercalciurics since few significant changes occurred in overall urinary chemistry profiles. CCM-OJ did, however, significantly (P less than or equal to 0.05) increase urinary pH relative to milk in both sexes and urinary citrate concentration in women only. Both of these urinary parameters were significantly increased by CCM-OJ in both sexes relative to the basal period. The combined pH and citrate effects are recognized to protect against calcium oxalate stone formation through formation of the soluble calcium citrate salt. These data indicate that either milk or CCM-fortified orange juice can be consumed, at least within the limits tested, as a dietary source of calcium without increasing the risk of stone formation in a calcium-sensitive subpopulation. That the urine chemistries and crystallization of such calcium-sensitive individuals does not significantly change with the consumption of either beverage implies that the urine of normal individuals would be exceedingly unlikely to change as well. 相似文献
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The LY-1B Cell Lineage 总被引:5,自引:0,他引:5
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The speed with which insulin alters hepatocyte ultrastructure and glycogen levels in insulin-deficient rats has been studied. Insulin deficiency was induced with alloxan, followed by insulin treatment with regular and NPH insulin. Rats were killed at various times after the insulin injection, blood samples were obtained, plasma glucose levels were determined, and liver samples were prepared for electron microscopy and glycogen determinations. Plasma glucose levels in insulin-deficient rats declined to normal values by 4 hours post insulin, returning to insulin-deficient levels by 8 hours post insulin. Hepatic glycogen was considerably reduced in the insulin-deficient rats. By 1 hour post insulin hepatic glycogen increased, reached maximal levels by 8 hours, then declined to insulin-deficient levels by 36 hours. The ultrastructural appearance of both centrilobular and periportal hepatocytes from insulin-deficient rats showed abundant vesicular smooth endoplasmic reticulum (SER), decreased rough endoplasmic reticulum (RER), and enlarged RER intracisternal spaces. One-half hour post insulin, centrilobular hepatocytes were unchanged. In periportal hepatocytes, however, vesicular SER was no longer visible, the RER intracisternal spaces appeared normal, and the amount of RER had increased. By 1 hour post insulin the centrilobular hepatocytes showed similar ultrastructural changes. These changes became more pronounced in the next few hours and remained through 24 hours. By 36 hours both centrilobular and periportal hepatocytes appeared similar to those in the insulin-deficient rat. These results demonstrate the rapid and lobular-specific effects insulin has on the hepatocyte. 相似文献
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The 49,000-dalton (49-kDa) small nuclear inclusion (NI) protein of tobacco etch virus (TEV) has two distinct functions associated with it. An N-terminal segment is covalently attached to the genomic length RNA and likely involved in RNA replication, while the C-terminal half is associated with a proteolytic activity critical for genome expression. The junction delineating these two proteins has not been identified. We have analyzed naturally occurring cleavage products of TEV NI proteins and have identified a possible internal cleavage site between Glu and Gly residues at TEV 49-kDa NI protein amino acids 189-190. Similar 49-kDa-derived products are formed in cell-free translation studies in minor amounts upon the addition of excess amounts of NI protein. Cleavage of the 49-kDa (430 amino acids) protein is predicted to result in the formation of two products, 21-kDa (189 amino acids) and 27 kDa (241 amino acids) in size. Complementary DNA encoding the 27-kDa C-terminal portion of the 49-kDa protein gene was cloned into various DNA sequences. This allowed us to express the 27-kDa protein alone or as part of higher molecular weight polyproteins containing flanking TEV or foreign protein sequences. This 27-kDa amino acid sequence had a proteolytic activity similar to the 49-kDa-associated activity. 相似文献
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The proteolytic activity associated with the small nuclear inclusion protein (NIa proteinase) of tobacco etch virus (TEV), a potyvirus, catalyzes several cleavages at sites within the polyprotein derived from the TEV RNA genome. The homologous proteinase of tobacco vein mottling virus (TVMV), a closely related potyvirus, cleaves at similar, yet distinct, recognition sites. We examined these proteinases, in a cell-free cleavage system, in an attempt to define the biochemical basis of substrate specificity. Each proteinase was specific for its own cleavage site sequence in cell-free trans processing reactions, and no processing of the heterologous cleavage site was evident. Domains of the proteinase which were important in determining this substrate specificity were identified by generating hybrid proteinase genes containing both TEV and TVMV NIa proteinase coding sequences. Using site-directed mutagenesis and standard recombinant DNA techniques, plasmids were constructed which contained coding sequences for hybrid TEV-TVMV proteinases. These plasmids were expressed and tested in a cell-free environment for their ability to cleave both TEV and TVMV substrates. The data suggest that the carboxy-terminal 150 amino acids of the NIa protein contain the necessary information to specifically recognize a particular cleavage site sequence, and that specificity determinants are contained in at least three interactive subdomains within this region. 相似文献
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Site-directed ELISA with synthetic peptides representing the HIV transmembrane glycoprotein 总被引:7,自引:0,他引:7
Francesca Chiodi Agneta von Gegerfeldt Jan Albert Eva Maria Feny Hans Gaines Madeleine von Sydow Gunnel Biberfeld Elliot Parks Erling Norrby 《Journal of medical virology》1987,23(1):1-9
Two partially overlapping 19 and 22 amino acids long peptides representing a highly immunogenic site of the transmembranous glycoprotein (gp41) of human immunodeficiency virus (HIV) were used as antigen in ELISA tests. The results of antibody determination with this assay were compared with those of three or more conventional ELISAs and Western blot (WB) tests and radioimmunoprecipitation assay. Twenty-six sera from patients with AIDS or LAS and from asymptomatic carriers of HIV infection all showed a pronounced reaction in the peptide ELISA as well as positive results with other tests. In contrast, 27 sera from laboratory workers and blood donors were negative by all tests. A group of 39 blood donor sera, which had shown false positive or ambiguous results in the ELISAs and sometimes in WB tests employed for confirmation, also were negative in all cases with the peptide ELISA. Consecutive samples collected from individuals with primary HIV infection were also analyzed. In 6 out of 9 cases, the peptide ELISA revealed an antibody response within one month after onset of clinical symptoms and sensitivity for antibody detection equaled that of other ELISA tests. Eight sera from five West African persons infected with HIV-related viruses did not react in the peptide ELISA, reflecting differences in properties of the envelope components. The peptide ELISA used in this study appears to represent a simple technique employing chemically synthesized antigen for accurate and sensitive estimation of antibodies to the HIV group of nontransforming human retroviruses. 相似文献
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