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101.
102.
T. Morii T. Shiihara Y.C. Lee M.F. Manuel K. Nakamura T. Iijima K. Hoji 《International journal for parasitology》1981,11(3):187-190
Epizootiological surveys of Leucocytozoon caulleryi infection in chickens in Japan, Taiwan, Philippines, Singapore, Malaysia and Thailand were undertaken by means of the immunodiffusion test. The rate of infection of L. caulleryi confirmed by the examination of parasites in the peripheral blood of chickens coincided with that of positive antibody response in the immunodiffusion test. Antibodies against L. caulleryi were found in chickens in all the countries surveyed in the present investigation. The prevalence of L. caulleryi infection in chickens was confirmed by the immunodiffusion test. Several chickens in each country showed the presence of serum antigens of L. caulleryi at the times of serum sample collection. These results seemed to indicate that the immunodiffusion test is a method efficient enough to be applicable to the epizootiological surveys and diagnosis of L. caulleryi infection in chickens in the field. As a result, the antibodies or soluble antigens in the sera of chickens infected with L. caulleryi present, respectively, in each country may have the same immunological characters. 相似文献
103.
JoséLuis Avila Antonio Bretaña María Argelia Casanova Angela Avila Francisco Rodríguez 《Experimental parasitology》1979,48(1):27-35
A liquid medium was developed for the continuous cultivation of Trypanosoma cruzi. Among the several highly purified macromolecules tested only bovine liver catalase, horseradish peroxidase, lactoperoxidase, and bovine hemoglobin supported the continuous growth, at high yield, of mice-virulent Trypanosoma cruzi; other hemoproteins were inactive. Bovine liver catalase showed optimal Trypanosoma cruzi growth-promoting activity, parasites reaching 20 × 106 parasites/ml (95% epimastigotes) at about 10 days in most of the 45 subpassages to date. Furthermore, this protein in the incubation medium provided all the amino acid requirements of actively growing parasites, thus eliminating the need for exogeneous free amino acids. Additional experiments revealed that the hemoprotein's growth-promoting activity was independent of any enzymatic activity and that reconstituting the exact protein composition by means of exogeneous amino acids did not support parasite multiplication, suggesting the importance of the primary structure of the active proteins for growth-promoting activity. These active macromolecules supported the multiplication of five different strains of Trypanosoma cruzi, but did not support Leishmania brasiliensis or Leishmania mexicana proliferation, suggesting species specificity. 相似文献
104.
Summary In this paper are studied in E. coli K12 the influence of the bacterial Rec and phage Red recombination systems on the rescue of the O
+ gene from the prophage by a superinfecting O
- phage, UV irradiated or not. In the absence of UV irradiation the Red system produces more recombinants that does the Rec system, and its action requires DNA replication. The presence of UV lesions in the DNA facilitates the action of the Rec system, which is more efficient in this instance than the Red system and can act in the absence of DNA replication. In all cases, there is a cooperation between the two generalized recombination systems. 相似文献
105.
José Carreira José Manuel Andreu Manuel Nieto Emilio Muñoz 《Molecular and cellular biochemistry》1976,10(2):67-76
Summary Two new forms of the plasma membrane ATP-ase ofMicrococcus lysodeikticus NCTC 2665 were isolated from a sub-strain of the microorganism by polyacrylamide gel electrophoresis. One of them had a mol.wt of 368,000 and a very low specific activity (0.80 µ mol.min–1.mg protein–1) that could not be stimulated by trypsin. This form has been called BI (strain B, inactive). If the electrophoresis was carried out in the presence of reducing agents (i.e., dithiothreitol) and the pH of the effluent maintained at a value of 8.5 another form of the enzyme was obtained. This had a mol.wt of 385,000 and a specific activity of 2.5–5.0 µ mol.min–1.mg protein–1 that could be stimulated by trypsin to 5–10 µ mol.min–1.mg protein–1. This preparation of the ATPase has been called form BA (strain B, enzyme active). The subunit composition of both forms has been studied by sodium dodecyl sulphate and urea gel electrophoresis and compared to that of the enzyme previously purified from the original strain (form A). The three forms of the enzyme had similar and subunits, with mol.wt of about 50,000 and 30,000 dalton, respectively. They also had in common the component(s) of relative mobility 1.0, whose status as true subunit(s) of the enzyme remains yet to be established. However, subunit, that had a mol.wt of about a 52,500 in form A (Andreu
et al. Eur. J. Biochem. (1973) 37, 505–515), had a mol.wt similar to in form BI and about 60,000 in form BA. Furthermore BA usually showed two types of this subunit ( and) and an additional peptide chain () with a mol.wt of about 25,000 dalton. This latter subunit seemed to account for the stimulation by trypsin of form BA.Forms BA could be converted to BI by storage and freezing and thawing. Conventional protease activity could not be detected in any of the purified ATPase forms and addition of protease inhibitors to form BA failed to prevent its conversion to form BI. The low activity form (BI) was more stable than the active forms of the enzyme and also differed in its circular dichroism. These results show thatM. lysodeikticus ATPase can be isolated in several forms. Although these variations may be artifacts caused by the purification procedures, they provide model systems for understanding the structural and functional relationships of the enzyme and for drawing some speculations about its functionin vivo. 相似文献
106.
A wide range of tolerance to Li+ has been found among 12 different yeasts. Concentrations that do not allow long-term growth also arrest growth of an actively growing culture within 2–5 h. At the same concentrations protein and RNA synthesis are inhibited with little or no lag period (<50 min) but respiration is not affected at these concentrations. Lower concentrations that do not inhibit growth, may impair sporulation. For given extracellular conditions, intracellular Li+ concentrations are lower in the more tolerant yeast strains. 相似文献
107.
108.
A preparation of ATPase from the membranes of Micrococcus lysodeikticus, solubilized and more than 95 %. pure, showed two main bands in analytical polyacrylamide gel electrophoresis. They did not correspond to isoenzymes because one band could be converted into the other by exposure to a mildly alkaline pH value. The conversion was paralleled by changes in molecular weight, circular dichroism and catalytic properties. Denaturation by pH at 25 °C was followed by means of circular dichroism, ultracentrifugation and polyacrylamide gel electrophoresis. A large conformational transition took place in the acid range with midpoints at about pH = 3.6 (I = 10?4 M), 4.3 (I = 0.03 M) and 5.3 (I = 0.1 M). The transition was irreversible. Strong aggregation of the protein occurred in this range of pH. The final product was largely random coil, but even at pH 1.5 dissociation into individual subunits was not complete. However, partial dissociation took place at pH 5 (I = 0.028 M). At this pH value the enzyme was inactive, but 20–30 % of the activity could be recovered when the pH was returned to 7.5.In the alkaline region the midpoint of the transition occurred near pH = 11 (I = 0.028 M). The pK of most of the tyrosine residues of the protein was about 10.9. The unfolding was irreversible and the protein was soon converted into peptide species with molecular weights lower than those determined for the subunits by gel clectrophoresis in the presence of sodium dodecyl sulphate. Conventional proteolysis did not account for the transformation. 相似文献
109.
110.
Identification of a novel adhesion molecule in human leukocytes by monoclonal antibody LB-2 总被引:6,自引:0,他引:6
Manuel Patarroyo Edward A. Clark Jacqueline Prieto Carmela Kantor Carl G. Gahmberg 《FEBS letters》1987,210(2):127-131
Monoclonal antibody LB-2 to a surface antigen on human B cells, lymphoblast, monocytes and vascular endothelial cells largely inhibited adhesion among Epstein Barr virus-immortalized normal B cells (EBV-B) and concanavalin A-stimulated blood mononuclear cells (Con A-BMC) before and after phorbol ester treatment. The antibody inhibited to a lesser extent phorbol ester-induced aggregation of monocytes, U937 cells and fresh BMC and had virtually no inhibitory effect on the adhesion among enriched T cells and granulocytes. A surface glycoprotein band of 84 kDa was obtained from EBV-B cells by immunoprecipitation and gel electrophoresis. Immunological and biochemical studies clearly distinguished this molecule from gp90 and associated glycoproteins which also mediate leukocyte adhesion. 相似文献