全文获取类型
收费全文 | 9262篇 |
免费 | 548篇 |
国内免费 | 56篇 |
专业分类
耳鼻咽喉 | 68篇 |
儿科学 | 304篇 |
妇产科学 | 202篇 |
基础医学 | 1413篇 |
口腔科学 | 511篇 |
临床医学 | 1074篇 |
内科学 | 1641篇 |
皮肤病学 | 175篇 |
神经病学 | 784篇 |
特种医学 | 392篇 |
外国民族医学 | 2篇 |
外科学 | 1034篇 |
综合类 | 79篇 |
一般理论 | 3篇 |
预防医学 | 774篇 |
眼科学 | 98篇 |
药学 | 719篇 |
中国医学 | 24篇 |
肿瘤学 | 569篇 |
出版年
2022年 | 74篇 |
2021年 | 126篇 |
2020年 | 97篇 |
2019年 | 150篇 |
2018年 | 165篇 |
2017年 | 141篇 |
2016年 | 136篇 |
2015年 | 132篇 |
2014年 | 206篇 |
2013年 | 344篇 |
2012年 | 418篇 |
2011年 | 425篇 |
2010年 | 262篇 |
2009年 | 261篇 |
2008年 | 392篇 |
2007年 | 353篇 |
2006年 | 375篇 |
2005年 | 393篇 |
2004年 | 324篇 |
2003年 | 264篇 |
2002年 | 294篇 |
2001年 | 258篇 |
2000年 | 281篇 |
1999年 | 270篇 |
1998年 | 131篇 |
1997年 | 135篇 |
1996年 | 108篇 |
1995年 | 112篇 |
1994年 | 103篇 |
1993年 | 101篇 |
1992年 | 194篇 |
1991年 | 217篇 |
1990年 | 196篇 |
1989年 | 199篇 |
1988年 | 223篇 |
1987年 | 205篇 |
1986年 | 197篇 |
1985年 | 203篇 |
1984年 | 111篇 |
1983年 | 119篇 |
1982年 | 82篇 |
1981年 | 83篇 |
1980年 | 68篇 |
1979年 | 111篇 |
1978年 | 95篇 |
1977年 | 87篇 |
1976年 | 68篇 |
1975年 | 63篇 |
1974年 | 59篇 |
1973年 | 53篇 |
排序方式: 共有9866条查询结果,搜索用时 0 毫秒
41.
Segel MJ Aqeilan R Zilka K Lorberboum-Galski H Wallach-Dayan SB Conner MW Christensen TG Breuer R 《International journal of experimental pathology》2005,86(5):279-288
The role of lymphocytes in the pathogenesis of lung fibrosis is not clear, but the weight of the evidence supports a pro-fibrotic effect for lymphocytes. The high-affinity interleukin-2 receptor (haIL-2R) is expressed on activated, but not quiescent, T lymphocytes. This selective expression of haIL-2R provides the basis for therapeutic strategies that target IL-2R-expressing cells. We hypothesized that elimination of activated lymphocytes by IL-2R-targeted chimeric proteins might ameliorate lung fibrosis. We investigated the effects of IL-2-Bax, a novel apoptosis-inducing IL-2R-targeted chimeric protein, on bleomycin-induced lung injury in mice. Treatment groups included (i) a single intratracheal instillation of bleomycin and twice-daily intraperitoneal injections of IL-2-Bax; (ii) intratracheal bleomycin and intraperitoneal IL-2-PE66(4Glu), an older-generation chimeric protein; (iii) intratracheal bleomycin/intraperitoneal PBS; (iv) intratracheal saline/intraperitoneal PBS. Lung injury was evaluated 14 days after intratracheal instillation by cell count in bronchoalveolar lavage (BAL) fluid, semi-quantitative and quantitative histomorphological measurements and by biochemical analysis of lung hydroxyproline. Bleomycin induced a BAL lymphocytosis that was significantly attenuated by IL-2-Bax and IL-2-PE66(4Glu). However, morphometric parameters and lung hydroxyproline were unaffected by the chimeric proteins. These results show that IL-2-Bax reduces the lymphocytic infiltration of the lungs in response to bleomycin, but this effect is not accompanied by a decrease in lung fibrosis. 相似文献
42.
BACKGROUND: Surveys of the public in several countries have found that negative attitudes towards antidepressants are common. However, there has been little research into the factors associated with these attitudes. METHODS: A national survey of 999 Australian adults assessed beliefs about the helpfulness or harmfulness of antidepressants for a person with depression and suicidal thoughts. Associated factors investigated were as follows: sociodemographic characteristics, exposure to depression, ability to recognize depression, beliefs about other depression interventions, beliefs about long-term outcomes with and without treatment, beliefs about causes, and stigmatizing attitudes. RESULTS: Around a quarter of Australian adults believe that antidepressants would be harmful for a person who is depressed and suicidal. This group was less educated, had less exposure to depression, showed poorer recognition of depression, was less favorable about other standard interventions including psychological ones, was less pessimistic about the long-term outcome if the person did not have treatment, and was more likely to see depression as due to weakness and to be under the individual's control. LIMITATIONS: The survey did not directly ask about reasons for believing that antidepressants would be harmful. CONCLUSIONS: Belief in the harmfulness of antidepressants is associated with a general lack of exposure to depression, leading to an underestimation of its seriousness and of the necessity for intervention. 相似文献
43.
In the search for a serology tool for the diagnosis of nonpatent as well as patent infections with Oesophagostomum dentatum in pigs a water-soluble, unglycosilated antigen of about 30 kDa specific for the third-stage larvae of the parasite was purified
by ion-exchange chromatography. In Western blots, the antigen was first detected by antibodies at day 7 postinfection. Cross-reactivity
with O. quadrispinulatum, Ascaris suum, or Trichuris suis was not detected. It is suggested that this protein is a suitable tool for the species-specific serodiagnosis of O. dentatum infection in pigs.
Received: 15 June 1998 / Accepted: 28 September 1998 相似文献
44.
N A Thorn F S Nielsen C K Jeppesen B L Christensen O Farver 《Acta physiologica Scandinavica》1986,128(4):629-638
When uptake of L-[14C]ascorbic acid ([14C]AA) to various organs in guinea-pigs was studied after intracardiac injection, the adenohypophysis, pars intermedia, and the neurohypophysis had an uptake per milligramme protein which was about half of the uptake to the adrenals. Adrenal uptake was 20 +/- 2.8 pmol mg-1 protein microCi-1 injected. The uptake to the different parts of the hypophysis was considerably higher than the uptake to pancreas, liver, kidney, spleen and other organs. When isolated nerve endings (neurosecretosomes) from ox neurohypophyses were incubated with a medium containing labelled dehydroascorbic acid ([14C]DHA), the uptake was much slower than when the medium contained labelled ascorbic acid. The uptake of [14C]DHA showed a linear dependence on concentration, and was not influenced by addition of Mg2+ and ATP. Addition of Mg2+ + ATP, omission of Ca2+ and Mg2+ or exchange of Na+ in the medium with K+ had no effect on the uptake of ascorbic acid. When isolated secretory granules from ox neurohypophyses were incubated with a medium containing [14C]DHA, uptake was considerably faster than the uptake when they were incubated in a medium containing [14C]AA. The uptake of dehydroascorbic acid was linear with the concentration in the medium and was not changed by addition of Mg2+ ATP. Addition of 10 mM NH4Cl or exchange of 120 mM K+ in the incubation medium with Na+ did not change the uptake of dehydroascorbic acid. The contents of copper, zinc, iron and cobalt were determined in isolated nerve endings (A) and membranes (B) as well as in lysate (C) from isolated neurosecretory granules. The results (in nmol mg-1 protein) were for Cu: (A): 0.25 +/- 0.01 (SEM), (B): 0.67 +/- 0.16, (C): 0.22 +/- 0.06; for Zn: (A): 0.53 +/- 0.13, (B): 6.97 +/- 0.75, (C): 1.8 +/- 0.53; and for Fe: (A): 15.6 +/- 1.9, (B): 6.92 +/- 0.32, (C): 3.15 +/- 0.43. In all preparations the cobalt content was below the detection limit (less than 5 pmol mg-1 protein). 相似文献
45.
A storage telemetrical method using thermoluminescent (TL) dosimeters for long-term measurements of incorporated radioactive substances in unrestrained rats has been developed. The system has been used in combination with radiotelemetrical registration of the circadian temperature rhythm. By sequential replacement of double TL dosimeters (60 mg, CaSO4:Dy) through an implanted silicon tube, the concentration of different radionuclides can be determined over long periods. The persistence of the circadian temperature rhythm indicates that the animals were unaffected by the experimental conditions. The relative uncertainty of the dosimeter system and the temperature transmitter is approximately +/- 2% (SD) at 5 mR exposures and +/- 0.05 degrees C, respectively. The weight of the system in total is 5.7 g. Disappearance studies (36-48 h) have been performed with the beta-emitters, 32P nad 42K, in subcutaneous tissues and tumor tissue. This TL method permits the repetition of an experiment on the same rat several times, and thereby avoids errors due to biological variations between animals. 相似文献
46.
A 23-year-old female with extreme hypercalcaemia was treated with calcitonin, mitramycin and parathyroidectomy and normocalcaemia was achieved after 4 weeks. Nevertheless, the patient later died of cutaneous necrosis, impaired circulation and multiple organ failure. Serum immunoreactive parathyroid hormone was in the normal range and parathyroid tissue normal. Mixed connective tissue disease was diagnosed on the basis of high titers of antibody to extractable nuclear antigen, moderately elevated levels of antibody to nuclear antigen and only marginal elevation of anti-double standed DNA. The role of Cl. difficile toxin in the blood and an acinic cell tumour is unclear. 相似文献
47.
Human mini-chromosomes in mouse embryonal stem cells 总被引:3,自引:2,他引:3
We have introduced human mini-chromosomes of 4 Mb and approximately 15 Mb
in size into mouse embryonal stem cells. Although these human mini-
chromosomes are stable in hamster and chicken cells, they re-arrange or
segregate aberrantly in the embryonal stem cells and are rapidly lost in
the absence of selection. However, one of the mini-chromosomes re-
arranged, acquired mouse centromeric sequences and was then stably
maintained for at least 60 population doublings in culture. This mini-
chromosome, which is 4 Mb in size, is a candidate for a mouse germ line
chromosome vector.
相似文献
48.
49.
Blood flow in skin, subcutaneous adipose tissue and skeletal muscle in the forearm of normal man during an oral glucose load 总被引:5,自引:0,他引:5
Blood flow to the forearm, and the subcutaneous tissue and skin in the forearm were measured by strain gauge plethysmography, 133Xe-elimination and Laser Doppler flowmetry during an oral glucose load (I g glucose kg-1 lean body mass) and during control conditions. The forearm blood flow remained constant during both experiments. Glucose induced a two-fold vasodilatation in subcutaneous tissue. In skin, glucose induced a relative vasodilatation and later a relative vasoconstriction compared with control experiments. When estimated from forearm blood flow and subcutaneous and skin blood flows, muscle blood flow decreased about 20-30% during both experiments. Proximal nervous blockade did not abolish the glucose-induced vasodilatation in subcutaneous tissue. In the glucose experiment, arterial glucose concentration increased to 7.8 +/- 1.17 mmol l-1 30 min after the load was given and then decreased to 4.5 +/- 0.34 mmol l-1 at the end of the experiment. In the control experiments glucose concentration was constant. Arterial noradrenaline concentration increased significantly from 1.0 +/- 0.13 to about 1.5 +/- 0.3 nmol l-1 120 min after glucose and remained at this level during the experiment. Similarly adrenaline increased from 0.16 +/- 0.11 to about 0.4 +/- 0.16 nmol l-1 180 min after glucose. It is hypothesized that the vasodilating effect of glucose in subcutaneous tissue is secondary to metabolic events connected to glucose uptake and energy deposition in adipose tissue. 相似文献
50.
Depression symptomatology was assessed up to four times at 2-year intervals on a sample of 2100 Danish twins initially aged 70 years and older. Data were analyzed using the biometric growth model approach proposed by Neale and McArdle (2000). Results show that occasion-specific depression is moderately and equally heritable in men and women (occasion-specific estimates of heritability ranged from 22% to 37%). Estimates of phenotypic variance, genetic variance, and heritability did not vary systematically across waves. In the best-fitting growth model, depression symptomatology was accounted for by two factors: (1) a level (i.e., average) effect that was highly heritable (estimate of 69% in women and 64% in men) and reflected overall vulnerability, and (2) a residual effect that was nonheritable and reflected occasion-specific circumstances that could either exacerbate or moderate inherited vulnerability. Attempts to identify specific genetic contributions to depression might profitably focus on average levels across multiple assessments, while attempts to identify specific environmental effects might profitably focus on deviations about this average. 相似文献