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141.
142.
George L. Wied Peter H. Bartels Marluce Bibbo May Chen Frank R. Reale Hans Schreiber Jaroslav J. Sychra 《Cell biochemistry and biophysics》1979,1(1):39-54
Cytologic preparations made from the tracheobronchial tree taken by the Schreiber catheter have been scanned by three color
microphotometry. The digitized cell images were processed by the analytical cytodiagnostic programs of the TICAS system. Cells
were sorted into two control groups and five groups of increasing atypia ranging from normal epithelium to invasive squamous
cell carcinoma. Standard statistical tests, including Wilk's Lambda, Rao's V, and the Kruskal-Wallis tests are performed on
these subsets of cell image features. This study demonstrates that discriminant analyses permit differentiation between normal
cells and those from marked atypia or carcinoma and that the classification achieves a high degree of agreement with visual
assignment. 相似文献
143.
The plasma membrane of mammalian cells can mediate the cytotoxic and cytocidal effects of colicin E3. As little as 102 lethal units of purified colicin E3 per cell exert a pronounced cytocidal effect on human epithelial HeLa cells and as little
as 104 lethal units per cell also on line L mouse fibroblasts in tissue culture. Cells in complete monolayers are rapidly killed,
become spherical and shrink, they are detached from the support and finally autolyzed. The percentage of killed cells in both
lines is directly proportional to the multiplicity of colicin used. Theld
50 for HeLa cells is about 30 times lower than for L cells. At the multiplicity of 105 l.u., usually 100 % HeLa cells and 90 % L cells are killed in 2–3 days. Purified colicins E2 and D have no demonstrable cytological
effect on HeLa cells, although DNA synthesis in L cells appears to be partly inhibited by colicin E2. The profound effect
of colicin E3 on mammalian cells could be interpreted in a similar way as in bacteria,viz. as a specific cleavage of rRNA. 相似文献
144.
145.
Simultaneous and stepwise deprotection of the fully benzylated D-glucosyl esters of 1-benzyl N-benzyloxycarbonyl- and N-tert-butyloxycarbonyl-L-glutamic acid (1 and 5, respectively) have been examined. Catalytic hydrogenation of 1 led to intramolecular aminolysis to give pyroglutamic acid and D-glucose, but similar treatment in the presence of trifluoroacetic acid afforded both anomers of 1-O-(L-gamma-glutamyl)-D-glucopyranose, which were characterized as trifluoroacetates (2alpha and 2beta) and converted into 2,3,4,6-tetra-O-acetyl-1-O-[1-methyl N-(acetyl)-L-glutam-5-oyl]-D-glucopyranose (4) which was also prepared by a definitive method. Hydrogenolysis of 5 gave both anomers of 1-O-[N-(tert-butyloxycarbonyl)-L-gamma-glutamyl]-D-glucopyranose (6), which, upon treatment with trifluoroacetic acid at - 10 degrees, afforded 2alpha and 2beta, respectively. The structure of 6beta was established by its conversion into 2,3,4,6-tetra-O-acetyl-1-O-[1-methyl N-(tert-butyloxycarbonyl)-L-glutam-5-oyl]-beta-D-glucopyranose (7beta), whereas similar treatment of 6alpha gave a mixture of 1,3,4,6-tetra-O-acetyl-2-O-[1-methyl N-(tert-butyloxycarbonyl)-L-glutam-5-oyl]-alpha-D-glucopyranose (9) and 7alpha. A 1 leads to 2 acyl migration occurred during esterification of the aglycon carboxyl group of 6alpha with diazomethane to give 2-O-[1-methyl N-(tert-butyloxycarbonyl)-L-glutam-5-oyl]-alpha-D-glucopyranose (8). 相似文献
146.
147.
148.
Citrobacter freundii was grown aerobically in a chemostat on a mineral medium witn galactose or glucose as carbon and energy sources under limitation
by carbon or nitrogen source respectively. At various specific growth rates ranging from 7 to 95% μmax the culture in steady state was analysed and growth yield, specific metabolic rate of substrate utilization, intracellular
concentration of pyruvate, ATP, ADP, AMP and energy charge were determined and plotted as functions of dilution rate. In all
four types of experiments the physiological state of cells remained practically independent of dilution rate up toD = 0.6 μmax, and at a given specific growth rate nearly independent on μmax and type of limitation. At approximatelyD = 0.6 μmax, which is close to the maximum output dilution rateD
m, the physiological state of the cells changed: growth yields decreased and intr cellular pyruvate and adenylates concentrations
increased. Consequently, in a given medium two dilution rates exist at which growth rate dx/dt is the same but the physiology
of the population is quite different. 相似文献
149.
150.
J Fantini J M Muller B Abadie A el Battari J Marvaldi A Tirard 《European journal of cell biology》1987,43(3):342-347
When HT 29 cells grown as a monolayer were incubated in a synthetic medium in presence of 0.1 microM [gamma 32P]-ATP, the radioactivity was incorporated predominantly into three major endogenous polypeptides of 123 kDa, 50 kDa and 46 kDa. The radioactive proteins could be detected as soon as 30 s after the addition of the labelled ATP. When exogenous substrates such as casein or phosvitin were added in the synthetic medium, these proteins became phosphorylated. The phosvitin-kinase activity was released in the culture medium following an incubation of the cells with phosvitin. Depletion of the enzymatic activity from the cell surface as well as competition between phosvitin and endogenous substrates led specifically to the inhibition of the 123 kDa polypeptide phosphorylation. At low density, endogenous phosphorylation increased with the cell number, whereas on the contrary it decreased at high cell density. We concluded that the surface of HT 29 cells expressed several protein kinase activities. We have characterized one of them as an ectophosvitin kinase which phosphorylated specifically a 123 kDa polypeptide and whose expression or accessibility varied according to cell density. 相似文献