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41.
Phosphoinositide 3-kinase is involved in the induction of the human sperm acrosome reaction downstream of tyrosine phosphorylation 总被引:7,自引:4,他引:3
Fisher HM; Brewis IA; Barratt CL; Cooke ID; Moore HD 《Molecular human reproduction》1998,4(9):849-855
In somatic cells phosphoinositide 3-kinase (PI 3-kinase) is activated upon
interaction with both receptor tyrosine kinases (RTK) and G- proteins
resulting in the production of moieties involved in the inositol
phospholipid signalling pathway. As G proteins, RTK and the inositol
phospholipids have all been implicated in the human sperm acrosome
reaction, experiments were carried out to determine whether PI 3-kinase was
also involved in this phenomenon. Wortmannin is a selective inhibitor of PI
3-kinase and was shown to significantly inhibit the acrosome reaction
induced by both mannose-bovine serum albumin (mannose-BSA) (10, 50 and 100
nM) and a polyclonal antibody raised against an extracellular region of the
sperm zona receptor kinase (ZRK, at 100 nM only). Wortmannin did not
inhibit the A23187- or progesterone-induced acrosome reaction. These
results suggest that PI 3- kinase is involved in the human sperm acrosome
reaction. The levels of tyrosine phosphorylation of sperm proteins as
detected by Western blotting using antiphosphotyrosine antibodies was not
affected by wortmannin in agonist (A23187 and mannose-BSA)-stimulated
spermatozoa. This indicated that PI 3-kinase operates downstream of
tyrosine phosphorylation in the signal transduction cascade which leads to
the human sperm acrosome reaction.
相似文献
42.
The objective of this study was to determine the impact of the learning
curve of one surgeon on the term delivery rate following laparoscopic
salpingostomy for tubal infertility. This was a retrospective audit of
ongoing clinical practice, undertaken in two tertiary level infertility
programmes. Subjects in this study were women undergoing surgery for total
occlusion of the distal Fallopian tube. The main outcome measure was
cumulative term delivery rates. On stepwise life-table analysis the length
of infertility, primary and secondary infertility, tubal diameter and
whether surgery was performed in the first or second half of the series
were significantly associated with outcome. These data suggest that there
is a learning curve in obtaining skills to perform laparoscopic
salpingostomy, that patient selection may improve with experience, and that
selection criteria should be emphasized during didactic teaching and the
preceptorship process.
相似文献
43.
44.
45.
1G10, a monoclonal IgM antibody that identifies a differentiation antigen on human granulocytes and a subpopulation of monocytes, was found to react specifically with glycosphingolipids bearing the Gal beta 1-4(Fuc alpha 1-3)GlcNAc hapten (X determinant). This carbohydrate determinant was found on both glycolipid and glycoprotein molecules isolated from HL-60 cells (a promyelocytic leukemia cell line). Thus, this highly conserved carbohydrate-defined determinant previously described on mouse embryonic and mouse and human carcinoma cells is also expressed as a tissue-specific differentiation antigen on normal human granulocytes. 相似文献
46.
47.
We investigated the binding of CCK to its receptors in the brain and pancreas of the ob/ob mouse, an animal model of inherited obesity. The binding of CCK to its receptors in the cerebral cortex was increased, and Scatchard analyses revealed that this increased binding was due to an increase in the number of receptor sites. By contrast, there was no increased binding to CCK receptors in other brain regions, including the hypothalamus, or to CCK receptors in the pancreas. In the db/db mouse, another animal model of inherited obesity, no changes in CCK binding to its receptors in cerebral cortex and other brain regions were detected. Our study demonstrates, therefore, that the ob/ob mouse has changes in brain CCK receptors and suggests that certain types of obesity in mice could be related to altered CCK binding and action. 相似文献
48.
Listeria monocytogenes phosphatidylinositol-specific phospholipase C has evolved for virulence by greatly reduced activity on GPI anchors 下载免费PDF全文
Wei Z Zenewicz LA Goldfine H 《Proceedings of the National Academy of Sciences of the United States of America》2005,102(36):12927-12931
Listeria monocytogenes phosphatidylinositol-specific phospholipase C (PI-PLC) plays a critical role in escape of this human pathogen from host cell vacuoles. Unlike classical bacterial PI-PLCs, the L. monocytogenes enzyme has very weak activity on glycosylphosphatidylinositol (GPI)-anchored proteins. Previous crystal structure analysis has revealed that a small beta-strand (Vb) is present in Bacillus cereus PI-PLC and is absent in the enzyme from L. monocytogenes. This Vb beta-strand in B. cereus PI-PLC forms contacts with the glycan linker of GPI anchors, which presumably increases its activity on GPI-anchored proteins. In this study, we show that, of all known bacterial PI-PLCs, those from listeriae are the only ones that lack the beta-strand. Expression by L. monocytogenes of B. cereus PI-PLC, which has strong activity on GPI-anchored proteins, inhibited bacterial escape from a vacuole and cell-to-cell spread, resulting in greatly reduced virulence in mice. Deletion of the Vb beta-strand from B. cereus PI-PLC abolished its ability to cleave GPI-anchored proteins, decreased its inhibitory effects, and increased its virulence in mice. These results strongly suggest that L. monocytogenes PI-PLC has evolved as an important determinant of L. monocytogenes pathogenesis by absence of the Vb beta-strand, thus leading to greatly reduced activity on GPI-anchored proteins. 相似文献
49.
K K Hartmann V Papa E J Brown U Doerries S M Rosenthal I D Goldfine 《Endocrinology》1990,127(4):2038-2040
A simple method was developed to isolate low abundance hormone receptor poly(A)+ RNA from cells in tissue culture. Adherent cells in tissue culture plates were directly released with proteinase K and solubilized in SDS. Oligo(dT) cellulose was directly added to the lysate to obtain poly(A)+ RNA. Yields and purity of the poly(A)+ RNA were comparable to other more lengthy methods. IGF-I receptor and insulin receptor mRNA could be detected on Northern blot without any degradation. 相似文献
50.
T B Kaye R A Rubin A B Goldfine K Rajamani B T Kinsley U M Vischer D C Simonson 《The Journal of clinical endocrinology and metabolism》1992,74(3):640-644
Because many of the clinical features associated with Cushing's syndrome are frequently found in patients with diabetes mellitus, diabetic patients are often evaluated for Cushing's syndrome. The initial test for Cushing's syndrome is the 1 mg overnight dexamethasone suppression test (DST), but its value as a screening test in diabetic subjects, especially those with poor glycemic control, has been questioned. To address this issue, an overnight DST was administered to 100 subjects with diabetes. Only 7 patients failed to suppress their plasma cortisol to less than 140 nmol/L (5.0 micrograms/dL), achieving a specificity of 93%. There was no relation between acute glycemic control (as measured by the mean of 4 serum glucose values obtained before receiving dexamethasone) or chronic glycemic control (as measured by glycohemoglobin) and false positive responses to the 1 mg overnight DST. The mean of the measures of acute glycemic control of the 7 subjects who had false positive results, 14.4 +/- 2.8 mmol/L, was not significantly different than that of the 93 subjects with normal responses, 13.2 +/- 3.3 mmol/L. Similarly, the mean glycohemoglobin of the subjects with false positive results, 12.8 +/- 2.4%, was not significantly different than that of the subjects with normal responses, 12.9 +/- 2.5%. There was no correlation between plasma cortisol after dexamethasone and glycohemoglobin (r = 0.05), and only a weak correlation with the mean serum glucose (r = 0.21). We conclude that the 1 mg overnight DST is a valid screening test for Cushing's syndrome in patients with diabetes, regardless of glycemic control. 相似文献