全文获取类型
收费全文 | 2769篇 |
免费 | 264篇 |
专业分类
3033篇 |
出版年
2023年 | 9篇 |
2022年 | 23篇 |
2021年 | 58篇 |
2020年 | 32篇 |
2019年 | 35篇 |
2018年 | 41篇 |
2017年 | 34篇 |
2016年 | 69篇 |
2015年 | 125篇 |
2014年 | 115篇 |
2013年 | 176篇 |
2012年 | 198篇 |
2011年 | 212篇 |
2010年 | 131篇 |
2009年 | 128篇 |
2008年 | 159篇 |
2007年 | 182篇 |
2006年 | 177篇 |
2005年 | 164篇 |
2004年 | 147篇 |
2003年 | 180篇 |
2002年 | 141篇 |
2001年 | 38篇 |
2000年 | 21篇 |
1999年 | 35篇 |
1998年 | 41篇 |
1997年 | 20篇 |
1996年 | 10篇 |
1995年 | 27篇 |
1994年 | 17篇 |
1993年 | 12篇 |
1992年 | 24篇 |
1991年 | 16篇 |
1990年 | 15篇 |
1989年 | 15篇 |
1988年 | 9篇 |
1987年 | 16篇 |
1986年 | 8篇 |
1985年 | 10篇 |
1984年 | 19篇 |
1983年 | 17篇 |
1982年 | 12篇 |
1981年 | 12篇 |
1980年 | 10篇 |
1978年 | 12篇 |
1977年 | 9篇 |
1974年 | 5篇 |
1973年 | 11篇 |
1972年 | 8篇 |
1971年 | 5篇 |
排序方式: 共有3033条查询结果,搜索用时 0 毫秒
11.
Valerie J. Horn Paul A. Sheehy Miriam B. Goodman Indu S. Ambudkar 《Molecular and cellular biochemistry》1991,101(1):43-49
Intracellular Ca2+ mobilization events were assessed in mouse L cells, which contain native prostaglandin E1 receptors and transfected human 2 adrenergic receptors. Both Fura2 (single cell measurements) and Quin 2, (cuvette assays) were used to determine [Ca2+]i levels. Our results demonstrate that in the transfected cells there is a dose-dependent increase in [Ca2+]i in response to isoproterenol (0.1 nM–100 nM), which is inhibited by the -adrenergic antagonist, propranolol, and is a result of intracellular Ca2+ release. [Ca2+]1 in these cells was also increased by prostaglandin E1, 8 bromo cyclic AMP, and aluminum fluoride. Both 8 bromo cAMP and isoproterenol induced a rapid increase in the levels of IP1, IP2, and IP3. The data presented demonstrate that the elevation of intracellular cyclic AMP induces an increase in IP3 production which leads to an elevation in [Ca2+];. We propose that this cyclic AMP dependent activation of the IP3 generating system occurs at a post-receptor site.Abbreviations cAMP
Adenosine Cyclic 3-5-Monophosphate
- [Ca2+]i
intracellular [Ca2+]i
- 8 Br cAMP
8 Bromo Adenosine Cyclic 3-5-Monophosphate
- DAG
Diacylglycerol
- EGTA]
[Ethylene Bis (oxyethylenenitrilo)] Tetracetic acid
- BSA
Bovine Serum Albumin
- HBSS-H
Hanks' Balanced Salt Solution buffered with HEPES to pH 7.4
- HEPES
4-(2-Hydroxyethyl)-1-piperazineethanesulfonic acid
- PIP2
Phosphatidylinositol 4,5-bisphosphate
- IP2
Inositol 4 Phosphate
- IP2
Inositol 4,5 Bisphosphate
- IP3
Inositol Trisphosphate
- PGE1
Prostaglandin E1
- PBS
Phosphate Buffered Saline Solution 相似文献
12.
Gibberellins (GAs) A17, A19, A20, A29, A44, 2OH-GA44 (tentative) and GA29-catabolite were identified in 21-day-old seeds of Pisum sativum cv. Alaska (tall). These GAs are qualitatively similar to those in the dwarf cultivar Progress No. 9 with the exception of GA19 which does not accumulate in Progress seeds. There was no evidence for the presence of 3-hydroxylated GAs in 21 day-old Alaska seeds. Dark-grown shoots of the cultivar Alaska contein GA1, GA8, GA20, GA29, GA8-catabolite and GA29-catabolite. Dark-grown shoots of the cultivar Progress No.9 contain GA8, GA20, GA29 and GA29-catabolite, and the presence of GA1 was strongly indicated. Quantitation using GAs labelled with stable isotope showed the level of GA1 in dark-grown shoots of the two cultivars to be almost identical, whilst the levels of GA20, GA29 and GA29-catabolite were significantly lower in Alaska than in Progress No. 9. The levels of these GAs in dark-grown shoots were 102- to 103-fold less than the levels in developing seeds. The 2-epimer of GA29 is present in dark-grown-shoot extracts of both cultivars and is not thought to be an artefact.Abbreviations cv
cultivar
- GAn
gibberellin An
- GC
gas chromatography
- GC-MS
combined gas chromatographymass spectrometry
- HPLC
high-pressure liquid chromatography
- KRI
Kovats retention index
- MeTMSi
methyl ester trimethylsilyl ether 相似文献
13.
J. V. Moore Ramona Moses Valerie J. Cowie 《Radiation and environmental biophysics》1985,24(3):211-218
Summary The gross growth rate, histology, cellular kinetics, andin situ radiobiological response have been measured for three murine, keratinising squamous cell carcinomas that differed in their degree of differentiation. Growth rate was fastest in the least-differentiated tumour, slowest in the best-differentiated. However, the kinetics of the compartment of undifferentiated cells that are likely to be radiotherapeutically important, were the same for the three lines. There was no correlation between degree of differentiation and intrinsic or apparent radiosensitivity as measured by the growth delay assay. The radiobiologically best-oxygenated tumour was that which had the largest stromal component and this was not the best-differentiated tumour. 相似文献
14.
M.D. M.P.H. Valerie M. Parisi B.S. Terrance M. Phernetton Ph.D. John H.G. Rankin 《Prostaglandins & other lipid mediators》1985,30(1):125-130
We have previously shown that FPL 55712, a specific leukotriene receptor antagonist, potentiates estrogen induced uterine hyperemia in nonpregnant rabbits. We therefore chose to investigate the vascular responses of pregnant rabbits to leukotriene blockade. Nine unanesthetized animals carrying 46 viable fetuses were used in this study. Regional blood flows were measured by the radioactive microsphere technique. In 5 rabbits control blood flows were measured after vehicle administration and FPL 55712, 1 mg/kg bolus, followed by infusion of 100 ug/kg/min was given via the jugular vein. Regional blood flows were measured again after 10 minutes of infusion. The procedural order was reversed in the remaining 4 animals. Resistance was calculated as mean arterial pressure divided by total flow to an organ. FPL 55712 decreased the blood pressure from 83 ± 2 to 76 ± 3 mmHg (P<.001). Uterine resistance was not significantly changed (387 ± 44 to 362 ± 42 mmHg·ml−1·min·gm), but renal resistance fell from 18.5 ± 1.1 to 15.1 ± 1.2 mmHg·ml−1·min·gm (P<.01). FPL 55712 induced maternal placental vasodilatation with resistance decreasing from 291 ± 33 to 261 ± 31 mmHg·ml−1·min·gm (P<.04). Vehicle administration did not cause dilation in any vascular bed. FPL 55712 appears to be a placental vasodilator whose action is most likely due to receptor blockade of the vasoconstrictive endogenous leukotrienes. 相似文献
15.
A new simple and sensitive in-vitro method for the diagnosis of type 1 (IgE-mediated) hypersensitivity in man is described. Sliced human skin is passively sensitized by reaginic serum from allergic patients and the presence of antigen-specific IgE on the sensitized slices is detected by assay of antigen-evoked histamine release. Serum from 12 out of 14 patients with clinical respiratory allergy and positive skin tests gave significant antigen-specific histamine release. This method, which is essentially an in-vitro model of the Prausnitz-Küstner reaction, should prove of value in the diagnosis of human reaginic hypersensitivity in man. 相似文献
16.
Joseph Dancis Rody P. Cox Peter H. Berman Valerie Jansen M. Earl Balis 《Biochemical genetics》1969,3(6):609-615
Radioautographic examination of skin fibroblasts grown in tissue culture from normal donors revealed heavy labeling of almost all cells following incubation with tritiated hypoxanthine. Cells from patients with Lesch-Nyhan's disease, lacking inosinate pyrophosphorylase, had only 10 grains or less per cell. When normal and abnormal cells were mixed prior to culture, there was a progressive increase, with culture time, in the percentage of heavily labeled cells so that by 96 hr, when the cells were confluent, over 95% of the cells were heavily labeled. Reduction of cell density by subculture produced a reversion to original values. Cultures from three obligatory heterozygotes revealed the expected mixed population of cells. This appears to be a practical approach to the identification of the heterozygote.Aided by USPHS CA08748 and GM15508, and the Health Research Council of the City of New York. 相似文献
17.
18.
19.
20.