全文获取类型
收费全文 | 665篇 |
免费 | 99篇 |
国内免费 | 1篇 |
专业分类
765篇 |
出版年
2018年 | 4篇 |
2017年 | 7篇 |
2016年 | 7篇 |
2015年 | 12篇 |
2014年 | 6篇 |
2013年 | 15篇 |
2012年 | 18篇 |
2011年 | 15篇 |
2010年 | 15篇 |
2008年 | 15篇 |
2007年 | 20篇 |
2006年 | 21篇 |
2005年 | 24篇 |
2004年 | 30篇 |
2003年 | 14篇 |
2002年 | 30篇 |
2001年 | 25篇 |
2000年 | 20篇 |
1999年 | 31篇 |
1998年 | 10篇 |
1997年 | 11篇 |
1996年 | 8篇 |
1995年 | 6篇 |
1994年 | 9篇 |
1993年 | 13篇 |
1992年 | 28篇 |
1991年 | 23篇 |
1990年 | 13篇 |
1989年 | 16篇 |
1988年 | 24篇 |
1987年 | 29篇 |
1986年 | 25篇 |
1985年 | 26篇 |
1984年 | 10篇 |
1983年 | 21篇 |
1982年 | 10篇 |
1981年 | 6篇 |
1980年 | 11篇 |
1979年 | 14篇 |
1978年 | 19篇 |
1977年 | 10篇 |
1976年 | 8篇 |
1975年 | 11篇 |
1974年 | 13篇 |
1973年 | 8篇 |
1971年 | 6篇 |
1970年 | 10篇 |
1969年 | 4篇 |
1967年 | 5篇 |
1966年 | 5篇 |
排序方式: 共有765条查询结果,搜索用时 15 毫秒
51.
Extracellular siderophores of rapidly growing Aspergillus nidulans and Penicillium chrysogenum
下载免费PDF全文
![点击此处可从《Journal of bacteriology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
G Charlang R M Horowitz P H Lowy B Ng S M Poling N H Horowitz 《Journal of bacteriology》1982,150(2):785-787
The highly active extracellular siderophores previously detected in young cultures of Aspergillus nidulans and Penicillium chrysogenum have been identified as the cyclic ester fusigen (fusarinine C), and its open-chain form, fusigen B (fusarinine B). 相似文献
52.
Paul M. Horowitz 《Analytical biochemistry》1978,86(2):751-753
A new method for isolating crystalline bovine liver thiosulfate sulfurtransferase has been developed which relies on the selective binding of the enzyme to agarose-immobilized Cibacron Blue F3GA. This preparation has the advantages of simplicity, reproducibility, and rapidity. It is also suggested that the introduction of a binding and elution step will materially aid previously published procedures. 相似文献
53.
Isolation and identification of the conidial germination factor of Neurospora crassa. 总被引:9,自引:5,他引:4
下载免费PDF全文
![点击此处可从《Journal of bacteriology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
The germination-essential substance (germination factor [GF]) that is lost from conidia of Neurospora crassa on exposure to solutions of low water activity has been isolated and identified as a group of iron-transport compounds, or siderochromes. The principal siderochrome of conidia is ferricrocin, a cyclic hexapeptide. A closely related substance, ferrichrome C, is tentatively identified as a minor constituent. The same substances are also present in extracts of mycelium along with small amounts of a third siderochrome, which has not been identified. The GF activity of culture filtrates is due to coprogen, the only siderochrome previously identified with N. crassa. 相似文献
54.
55.
M Columbo E M Horowitz L M Botana D W MacGlashan B S Bochner S Gillis K M Zsebo S J Galli L M Lichtenstein 《Journal of immunology (Baltimore, Md. : 1950)》1992,149(2):599-608
The gene product of the steel locus of the mouse represents a growth factor for murine mast cells and a ligand for the c-kit proto-oncogene receptor, a member of the tyrosine kinase receptor class of oncogenes (for review, see O. N. Witte. 1990. Cell 63:5). We have studied the effect of the human recombinant c-kit receptor ligand stem cell factor (rhSCF) on the release of inflammatory mediators from human skin mast cells and peripheral blood basophils and compared its activity to that of rhIL-3, rhSCF (1 ng/ml to 1 microgram/ml) activated the release of histamine and PGD2 from mast cells isolated from human skin. Analysis by digital video microscopy indicated that purified human skin mast cells (84 +/- 5% pure) responded to rhSCF (0.1 to 1 microgram/ml) challenge with a rapid, sustained rise in intracellular Ca2+ levels that was accompanied by secretion of histamine. A brief preincubation (10 min) of mast cells with rhSCF (0.1 pg/ml to 1 ng/ml) significantly enhanced (100 +/- 35%) the release of histamine induced by anti-IgE (3 micrograms/ml), but was much less effective on IgE-mediated release of PGD2. In contrast, a short term incubation with rhSCF did not potentiate the secretion of histamine activated by substance P (5 microM). A 24-h incubation of mast cells with rhSCF did not affect the release of mediators induced by anti-IgE (3 micrograms/ml), probably due to receptor desensitization, rhSCF (1 ng/ml to 3 micrograms/ml) neither caused release of histamine or leukotriene C4 (LTC4) release from leukocytes of 14 donors, nor induced a rise in intracellular Ca2+ levels in purified (greater than 70%) basophils. Brief preincubation (10 min) of leukocytes with rhSCF (1 ng/ml to 3 micrograms/ml) caused an enhancement (69 +/- 11%) of anti-IgE-induced release of histamine that was significant at concentrations as low as 3 ng/ml (p less than 0.05), whereas it appeared less effective in potentiating IgE-mediated LTC4 release. In contrast, a prolonged incubation (24 h) with rhSCF (0.1 pg/ml to 100 ng/ml) did not enhance the release of histamine or LTC4 induced by anti-IgE (0.1 microgram/ml), whereas rhIL-3 (3 ng/ml) significantly potentiated the release of both mediators.(ABSTRACT TRUNCATED AT 400 WORDS) 相似文献
56.
Farrelly AM Ro S Callaghan BP Khoyi MA Fleming N Horowitz B Sanders KM Keef KD 《American journal of physiology. Gastrointestinal and liver physiology》2003,284(6):G883-G895
Previous studies suggest that ether-a-go-go related gene (ERG) KCNH2 potassium channels contribute to the control of motility patterns in the gastrointestinal tract of animal models. The present study examines whether these results can be translated into a role in human gastrointestinal muscles. Messages for two different variants of the KCNH2 gene were detected: KCNH2 V1 human ERG (HERG) (28) and KCNH2 V2 (HERG(USO)) (13). The amount of V2 message was greater than V1 in both human jejunum and brain. The base-pair sequence that gives rise to domains S3-S5 of the channel was identical to that previously published for human KCNH2 V1 and V2. KCNH2 protein was detected immunohistochemically in circular and longitudinal smooth muscle and enteric neurons but not in interstitial cells of Cajal. In the presence of TTX (10(-6) M), atropine (10(-6) M). and l-nitroarginine (10(-4) M) human jejunal circular muscle strips contracted phasically (9 cycles/min) and generated slow waves with superimposed spikes. Low concentrations of the KCNH2 blockers E-4031 (10(-8) M) and MK-499 (3 x 10(-8) M) increased phasic contractile amplitude and the number of spikes per slow wave. The highest concentration of E-4031 (10(-6) M) produced a 10-20 mV depolarization, eliminated slow waves, and replaced phasic contractions with a small tonic contracture. E-4031 (10(-6) M) did not affect [(14)C]ACh release from enteric neurons. We conclude that KCNH2 channels play a fundamental role in the control of motility patterns in human jejunum through their ability to modulate the electrical behavior of smooth muscle cells. 相似文献
57.
Brianne E. Docter Scott Horowitz Michael J. Gray Ursula Jakob James C.A. Bardwell 《Nucleic acids research》2016,44(10):4835-4845
Organisms use molecular chaperones to combat the unfolding and aggregation of proteins. While protein chaperones have been widely studied, here we demonstrate that DNA and RNA exhibit potent chaperone activity in vitro. Nucleic acids suppress the aggregation of classic chaperone substrates up to 300-fold more effectively than the protein chaperone GroEL. Additionally, RNA cooperates with the DnaK chaperone system to refold purified luciferase. Our findings reveal a possible new role for nucleic acids within the cell: that nucleic acids directly participate in maintaining proteostasis by preventing protein aggregation. 相似文献
58.
E.R. Berman J. Horowitz N. Segal S. Fisher L. Feeney-Burns 《Biochimica et Biophysica Acta (BBA)/General Subjects》1980,630(1):36-46
The kinetic properties and subcellular distribution of an esterifying enzyme in the pigment epithelium of bovine retina have been studied using both [1-3H]retinol and [3H]retinol bound to cellular retinol-binding protein as substrates. The most active esterifying fraction in pigment epithelial cell preparations was the microsomes, but the lysosome plus mitochondria fraction also showed some activity, probably due to endoplasmic reticulum present as an impurity. The microsomal enzyme showed optimum activity at pH 7.5, and the reaction was linear up to 30 μg protein and for the first 10–15 min. The apparent Km values were 16.6 · 10?6 and 5.5 · 10?6 M for [3H]retinol and bound [3H]retinol, respectively. This is the first time that retinol bound to cellular retinol-binding protein has been shown to undergo metabolic stransformation. The microsomal esterifying activity was destroyed by boiling for 1 min, or after freezing for 2 months. No clear requirement for ATP, CoA or fatty acid could be demonstrated.Of all the other tissues examined under the same experimental conditions as those used for the pigment epithelium, onlt intestine showed measurable activity. With larger amounts of tissue protein and longer incubation periods, activity was also detectable in microsomes of liver, testis and retina 相似文献
59.
60.