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861.
V. Cusumano G.B. Costa R. Trifiletti R.A. Merendino G. Mancuso 《FEMS immunology and medical microbiology》1995,10(2):151-156
Abstract Contamination of food with mycotoxins is a major health problem. Impairment of several immune functions has been repeatedly reported in animals fed with contaminated fodder. Since the liver is a major target of toxicity by aflatoxins, the effects of aflatoxins B1, and its hepatic metabolites Q1 and M1 on Kupffer cell function was investigated in vitro. Aflatoxin B1 induced significant ( P < 0.05) inhibition of phagocytosis, intracellular killing of Candida albicans , and intrinsic anti-Herpes virus activity at concentrations as low as 0.01 pg ml−1 . Aflatoxin Q1 and M1 had similar effects on phagocytosis and microbicidal activity, but were two- to ten-fold less potent than aflatoxin B1 . 相似文献
862.
In the fowl the primordial germ cells accumulate in the germinal crescent to the anterior of the two-day embryo. A simple ballistic device has been used to fire tungsten particles (mean diameter 1.5 m) into this region. By coating these projectiles with vector DNA it is possible to transfect these cells. Hatchlings produced by this technique were raised to sexual maturity and shown to contain the foreign DNA in their sperm. G1 offspring containing this DNA were also produced in roughly 20% of these cockerels. In the majority of cases the vector DNA disappeared from the G1 generation as they matured suggesting that in these cases it had been transmitted episomally. 相似文献
863.
内皮素-1对缺氧肺动脉平滑肌细胞的增殖作用 总被引:2,自引:0,他引:2
内皮素(ET)是至今所发现的最强的内源性血管收缩肽,近年来发现ET-1能促进血管平滑肌细胞增殖。本研究表明ET-1对缺氧培养的肺动脉平滑肌细胞(PASMC)有剂量依赖的增殖作用,缺氧可促进PASMC的DNA合成且增加ET-1的丝裂原作用。ET-1的丝裂原作用主要由其A型受体(ETR_A)所介导,ETR_A的特异拮抗剂BQ123可显著抑制缺氧以及缺氧与ET-1协同所产生的增殖作用,而且发现ETR_A在缺氧培养的PASMC中的表达显著高于常氧对照组PASMC。本研究表明ET-1参与了缺氧性肺动脉结构重组,而缺氧可增强PASMC对ET-1的增殖反应性。 相似文献
864.
组胺对培养新生大鼠心肌细胞自发性搏动及动作电位的影响 总被引:1,自引:0,他引:1
以培养大鼠乳鼠心肌细胞为模型,观察组胺对培养心肌细胞自发性搏动频率及动作电位的影响。结果表明:组胺0.1-10umol/L可以引起剂量依赖性的心肌细胞搏动频率的增快,而且这种效应呈时间依赖性。组胺10umol/L可以使心肌细胞动作电位的幅度(APA),最大上升速率(Vmax)及超射(OS)明显增加,动作电位持续时间(APD50和APD90)明显延长,窦性周长(SCL)明显缩短。以上结果提示,组胺致 相似文献
865.
大鼠颈上神经节烟碱电流的整流及失敏 总被引:1,自引:0,他引:1
在培养的新生大鼠颈上神经节交感神经元标本上,用全细胞膜片钳技术研究了烟碱型乙酰胆碱受体(nAChR)通道的整流及失敏现象。烟碱激动剂引起的全细胞电流在膜电位为负值时随膜电位呈线性改变,而在膜电位达+60mV时仍不出现外向电流,表现出强烈的内向整流。nAChR通道电流存在失敏现象,即持续恒压喷射激动剂所引起的全细胞电流随时间呈指数衰减,不能保持在峰值水平,失敏随激剂浓度呈量效关系,膜电位的超极化也加 相似文献
866.
The distribution of immunoreactive alpha-melanocyte stimulating hormone (alpha-MSHI) in the rat lower brain stem was examined by indirect immunofluorescence or peroxidase- anti-peroxidase immunohistochemical method using an antiserum against synthetic alpha-MSH. The results confirmed the presence of alpha-MSHI fibers in the midbrain central gray matter and parabrachial area, and demonstrated a much more extensive distribution of these fibers in various parts of the lower brain stem areas previously thought not contain alpha-MSHI fibers. In addition, the commissural nucleus was identified as a new alpha-MSHI neurons-containing site. No alpha-MSHI neurons were seen in other regions of the rat lower brain stem. 相似文献
867.
Massimo De Felici 《Molecular reproduction and development》1984,10(4):423-432
Fluorescent lectins were used to study the chemical nature of carbohydrate moieties present on the surface of female and male germ cells isolated from mouse gonads during fetal and early posnatal development. Concanavalin A (ConA), lens culinaris agglutinin (LCA), ricinus communis agglutinin (RCAI) and wheat germ agglutinin (WGA) bound intensely to the germ cell plasma membrane at all stages studied. Other lectins such as ulex europaeus agglutinin (UEAI) and agglutinin (SBA) did not bind or bound moderately (SBA to female germ cells only). Distinct developmental-related changes were observed when female germ cells were labeled with fluorescein-conjugated peanut agglutinin (PNA) or dolichos biflorus agglutinin (DBA). DBA and PNA binding was absent or weak in fetal female and male germ cells, but became intensely positive in oocytes in the immediate postnatal period. The percentage of oocytes stained with DBA increased during the first three days after birth, and from day 3–4 onwards all oocytes were strongly labeled. I suggest that these changes in lectin binding reflect changes in biochemical structure of the oocyte surface related to differentiative events occurring in the mouse ovary immediately after birth. 相似文献
868.
Lynn R. Trusal Albert W. Guzman Carol J. Baker 《In vitro cellular & developmental biology. Plant》1984,20(4):353-364
Summary The pathophysiology of endothelial cells is important to a variety of vascular conditions including coagulation and hemostasis
resulting from clinical frostbite. Use of an in vitro model system demonstrated that when bovine endothelial cells were frozen
at 1°C or 20°C/min and thawed immediately (20°C/min), a variety of ultrastructural alterations occurred. Membraneous structures
were most extensively damaged, with mitochondria the most sensitive organelle. Low amplitude mitochondrial swelling, first
evident at 0°C, progressed to high amplitude swelling by −10°C (frozen). In addition, the rough endoplasmic reticulum was
dilated and formed large vesicles with a homogeneous matrix. Nuclear changes first occurred at −15°C. These included separation
and distortion of the nuclear membrane, changes in chromatin distribution, and disruption of the nucleolus. Scanning electron
microscopy revealed perforated plasma membranes in some cells at −10°C (frozen) and in most cells by −20°C. Cultures frozen
at 20°C/min revealed mostly the same ultrastructural damage noted at 1°C/min except a higher percentage of cells exhibited
alterations. Data from the recovery index and lactic dehydrogenase (LDH) release correlated well with observed ultrastructural
changes. Early swelling of mitochondria and dilation of rough endoplasmic reticulum was not lethal in the absence of freezing.
Increased swelling in cytoplasmic organelles coupled with nuclear alterations at −15°C resulted in a decreased survival rate
and release of significant quantities of LDH by −20°C. No unique morphological changes were temperature specific, but the
total number of cells that displayed alterations increased as temperature decreased.
The views, opinions or findings, or both, contained in this report are those of the authros and should not be construed as
indicative of an official Department of the Army position, policy, or decision unless so designated by other official documentation. 相似文献
869.
Michael Ma Shuenn-Jue Wu Maureen Howard Alexej B. Borkovec 《In vitro cellular & developmental biology. Plant》1984,20(9):739-742
Summary We report here that the use of murine thymoma cell EL-4 conditioned medium enhances hybridoma yield in a low-antigen dose
in vitro immunization protocol. This improved protocol allowed the production of a panel of monoclonal antibodies toDrosophila yolk proteins using less than 1 nanomole of antigen. We believe this refinement will be valuable for the application of hybridoma
technology to biologically active materials that are hard to isolate and purify due to their low concentration in the biological
fluids.
This research was supported by the College of Agriculture and Life Sciences, University of Maryland, USDA-University of Maryland
Cooperative
Editor's Statement This observation should simplify in vitro immunization approaches and shed new light on the factors required
for the in vitro immune response. Wallace L. McKeehan 相似文献
870.
M. Jose Comez-L Pilar Lopez Jose V. Castell 《In vitro cellular & developmental biology. Plant》1984,20(11):826-832
Summary The present study was undertaken to define the conditions for optimal cryopreservation of hepatocytes. Two different freezing
procedures were analyzed: a slow freezing rate (SFR) (−2° C/min down to −30°C and then quick freezing to −196° C) and a fast
freezing rate (FFR) (direct freezing of tubes to −196° C: −39° C/min). Cells were frozen in fetal bovine serum containing
10% Dimethyl sulfoxide (DMSO). After rapid thawing at 37° C, followed by dilution and removal of the cryoprotectant, cells
were plated and several parameters were followed as criteria for optimal cryopreservation of cells. The FFR cells showed no
apparent ultrastructural damage after 24 h of culture. Plating efficiency and spreading were similar as controls. Gluconeogenesis
from pyruvate and fructose, tyrosine amino transferase induction by glucagon and dexamethasone, urea production, and plasma
protein synthesis of FFR cells were similar to those found in control cultures. The FFR procedure, in comparison to the SFR
method, seemed to render the best preserved hepatocytes.
The financial support for this work was from Fondo de Investigaciones Sanitarias de la Seguridad Social, Grants 41/82 and
48/82. 相似文献