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941.
Improved histological localization of GABA-transaminase activity in rat cerebellar cortex after aldehyde fixation 总被引:1,自引:0,他引:1
Summary A method for the chemical fixation of the enzyme GABA-transaminase in nervous tissue is described. It is shown that after
perfusion with a formaldehyde/glutaraldehyde fixative, activity of the enzyme in cerebellar cortex is demonstrable whilst
cellular morphology is preserved. Results from the improved technique have shown new sites of GABA-transaminase activity in
cerebellar cortex. In view of these results a special function for glial cells in this area of brain has been suggested. 相似文献
942.
Salman Gailani William F. McLimans Annie Nussbaum Frances Robinson Oliver Roholt 《In vitro cellular & developmental biology. Plant》1976,12(5):363-372
Summary Two thin film culture systems, the controlled environment steady state system (SS) and the rocker tube configuration of that
system (RT), were used to identify some of the conditions that appear to maintain morphologic and functional characteristics
of cells of human bone marrow explants in vitro. The systems configuration assured continual gassing, control and easy monitoring
of the cultures. Cytocentrifuge preparations of media of specimens cultured in RT disclosed, though in decreasing numbers,
various hematopoietic cells for periods exceeding one month. Hematopoietic cells shed from specimens cultured in the SS system
were retained in the culture tubes; cells of the myelocytic series predominated for the first 2 weeks while an increasing
number of monocytes and macrophages appeared in the media of older cultures. Histologic examination of cultured explants disclosed
preservation of the marrow architecture and the persistence of hematopoietic cells. Specimens cultured in RT tubes tended
to be less cellular than similar cultures placed in dialysis bags or as cultured in the SS system. Immunoglobulins (Ig) were
released into the culture media at a constant rate throughout the period of culture. Specimens that were cultured at a controlled
pH of 7.4 released 2 to more than 4 times as much Ig as similar specimens maintained at a pH level of 7.1. There were no definitive
differences in Ig levels in the cultures maintained at comparable pH levels and overlaid with various CO2 concentrations, i.e. 2%, 5%, 10%; similarly, no differences in Ig levels were found in specimens cultured in media containing
fetal bovine sera as opposed to horse sera.
Supported by U.S.P.H.S. Grant CA-5834 from the National Cancer Institute.
Department of Medicine A.
Department of Cell Physiology
Department of Immunology and Immunochemistry. 相似文献
943.
Janice Y. Chou Bruce D. Weintraub Saul W. Rosen Jacqueline Whangpeng Howard D. Sussman Joan R. Haughom J. C. Robinson 《In vitro cellular & developmental biology. Plant》1976,12(8):589-594
Summary Several cell lines, originally thought to be derived from a human placenta at term but possibly HeLa-contaminated, have been
studied. These cells secrete a protein indistinguishable immunochemically from the alpha subunit of chorionic gonadotropin
but not the beta subunit of chorionic gonadotropin or placental lactogen. Complete chorionic gonadotropin was detected but
amounted to less than 1% of the level of the alpha subunit. The cells also produce an alkaline phosphatase similar to placental
alkaline phosphatase in immunochemical, gel-electrophoretic, and heat-denaturation properties. They induce tumor growth when
inoculated into nude mice. These cells are aneuploid and have a model chromosome number of 66. The common HeLa karyologic
markers, designated 1, 2, and 3, and A-type glucose-6-phosphate dehydrogenase are present in these cells. HeLa cells have
not previously been shown to secrete theα subunit of hCG. 相似文献
944.
Survival time of brook trout (Salvelinus fontinalis Mitchill) at low pH was directly related to size, and inversely related to temperature. Between pH 2.50 and 3.25 an increase in pH by increments of 0.25 each led to a 2–3 fold increase in survival time. At higher pH's (3.25–3.75) elevations in pH by the same increments each produced a 3–5 fold increase. Brook trout tested at pH 3.35 and 3.50 showed maximum survival times in June-August. Members of seven inbred lines of brook trout were tested for acid tolerance; the lines differed markedly providing strong evidence that acid tolerance is hereditary. Tests involving either intercrossed or backcrossed offspring of tolerant or intolerant parentals demonstrated intermediate survival in 12.5% of all experiments and heterosis in 66.7% of the tests. Differences in survival of inbred lines were the most marked at pH 3.25. Exposure for 1 week at pH 3.75 resulted in a 20–25% decrease in survival time of 18 fish tested at pH 2.50 and 3.00. Out of a total of 24 trout (17 g) tested at pH 3.75 two highly tolerant individuals were still alive after 6.1 weeks. Thus it is likely that a strain resistant to a pH below 4.1, the previously recorded lower limit, can be developed by selective breeding. 相似文献
945.
Richard A. Firtel Andrew Cockburn Gary Frankel Vickers Hershfield 《Journal of molecular biology》1976,102(4):831-852
The genome of the cellular slime mold Dictyostelium discoideum has been analyzed by limit digestion with EcoR1 restriction endonuclease. Approximately 15% of the nuclear genome is cleaved into nine discrete fragments as analyzed by agarose gel electrophoresis. These fragments appear to be derived from two nuclear buoyant density satellites, one of which contains sequences coding for ribosomal RNA. The bulk of the nuclear DNA is digested into approximately 7000 fragments with a mean molecular weight of 4 × 106 to 5 × 106. The mitochondrial DNA is digested into four fragments. One of the nuclear bands has been cloned in Escherichia coli using plasmid pSC101 carrying tetracyline resistance. Analysis by renaturation kinetics indicates that it is repeated approximately 200 times per haploid genome and that it is not internally repeated. 相似文献
946.
Prof. Ann Andrew 《Cell and tissue research》1976,172(4):541-551
Summary The duodenum of 16-day Black Australorp chick embryos, and the duodenum, ileum, large intestine and caeca of 18-day embryos and of chicks within 30 h of hatching, have been studied by electron microscopy. Cells were found with secretory granules resembling those in mammalian EC, S, A-like, EG and D cells (terminology of Solcia et al., 1973), and were on this basis tentatively identified accordingly. The distribution and frequency of the chick cells in different parts of the tract correspond well to the situation in mammals.Supported by grants from the Senate Research Committee of the University of the Witwatersrand, JohannesburgThe author gratefully acknowledges the help of Professors E. Solcia and N. Ferreira 相似文献
947.
Physiological aging of champion runners 总被引:1,自引:0,他引:1
948.
949.
On incubation Days 9, 11, 12, 14, or 15, chick embryos were injected intravenously with 4.0 × 106L. donovani amastigotes. Embryos were incubated at 33 C immediately after infection. Numbers of amastigotes found in the liver 1 hr after injection increased as the age of embryo recipients increased. Most 14- or 15-day infected embryos hatched when allowed to do so, but many younger embryos were unable to survive at 33 C. Numbers of amastigotes in the liver of chicks, hatched after infection as embryos, decreased as the cloacal temperature of the chicks increased. Despite a 31 C incubation temperature, chicks exhibited a mean 38.3 C cloacal temperature 1 day after hatching.Chick fibroblast cultures were initiated as explants of embryo brain and infected with amastigotes from hamster spleen. Only amastigotes were seen in cultures kept at 37 C, but extracellular promastigotes and intracellular amastigotes were present in cultures at 33 C. Although promastigotes increased in number in the medium overlay at 33 C, amastigotes decreased in number at 33 C and 37 C. One intracellular amastigote was seen in a culture which had been incubated at 25 C after inoculation with promastigotes. 相似文献
950.
The enthalpy of the bioluminescent reaction has been studied by direct calorimetric methods. Bacterial luciferase, isolated from Beneckea harveyi (formerly strain MAV) has been used to catalyze the oxidation of reduced flavin mononucleotide (FMNH2) and a long chain aliphatic aldehyde (dodecanal, RCHO) by molecular oxygen to give the indicated products and blue-green light. The enthalpy measured for this process was found to be ΔHL = ?338.9 k.J (mol FMN)?1 (?81.0 kcal) at 25.00 °C and ?402.9 kJ (mol FMN)?1 (?96.3 kcal) at 7.00 °C. Calculations based on redox electrode potentials indicate a corresponding value of the free energy change, ΔGL = ?464.8 kJ (mol FMN)?1 (?111.1 kcal), at 25 °C. Measurements were performed in 0.15 m phosphate buffer, pH 7.0 and the values were arrived at by correcting the observed heats for the heat associated with the autoxidation process: FMNH2 + O2 ? FMN + H2O2; ΔHD = ?158.5 kJ (mol FMN)?1 (?37.8). These data and a detailed thermodynamic analysis have demonstrated the need for two parameters, referred to as the intrinsic free energy, ΔG1, and intrinsic enthalpy, ΔH1, which are functionally defined by the relations ΔGI = ΔGL ? uhvΔHI = ΔHL ? uhv, where u is the quantum yield of the reaction expressed in einsteins mole?1.These parameters reflect the thermochemistry of the bioluminescent reaction corrected for emitted photons. Thus, they are useful for comparing the thermochemistry of a chemiluminescent process. Their values for the bacterial luciferase system at 25 °C and pH 7.0 are ?391.6 and ?266.9 kJ (mol FMN)?1 (?93.6 and ?63.8 kcal), respectively, assuming a value of 0.3 for the quantum yield. The calorimetric data also suggest the existence of a long-lived species which persists after photon emission. 相似文献