全文获取类型
收费全文 | 3504篇 |
免费 | 211篇 |
国内免费 | 79篇 |
专业分类
耳鼻咽喉 | 10篇 |
儿科学 | 200篇 |
妇产科学 | 54篇 |
基础医学 | 352篇 |
口腔科学 | 72篇 |
临床医学 | 407篇 |
内科学 | 758篇 |
皮肤病学 | 95篇 |
神经病学 | 157篇 |
特种医学 | 401篇 |
外科学 | 214篇 |
综合类 | 420篇 |
一般理论 | 1篇 |
预防医学 | 212篇 |
眼科学 | 47篇 |
药学 | 164篇 |
2篇 | |
中国医学 | 2篇 |
肿瘤学 | 226篇 |
出版年
2022年 | 17篇 |
2021年 | 30篇 |
2020年 | 27篇 |
2019年 | 28篇 |
2018年 | 47篇 |
2017年 | 35篇 |
2016年 | 32篇 |
2015年 | 55篇 |
2014年 | 73篇 |
2013年 | 97篇 |
2012年 | 91篇 |
2011年 | 104篇 |
2010年 | 114篇 |
2009年 | 114篇 |
2008年 | 167篇 |
2007年 | 211篇 |
2006年 | 170篇 |
2005年 | 158篇 |
2004年 | 134篇 |
2003年 | 71篇 |
2002年 | 67篇 |
2001年 | 73篇 |
2000年 | 74篇 |
1999年 | 71篇 |
1998年 | 141篇 |
1997年 | 169篇 |
1996年 | 142篇 |
1995年 | 113篇 |
1994年 | 132篇 |
1993年 | 108篇 |
1992年 | 53篇 |
1991年 | 65篇 |
1990年 | 63篇 |
1989年 | 79篇 |
1988年 | 62篇 |
1987年 | 66篇 |
1986年 | 74篇 |
1985年 | 57篇 |
1984年 | 34篇 |
1983年 | 24篇 |
1982年 | 35篇 |
1981年 | 40篇 |
1980年 | 34篇 |
1979年 | 24篇 |
1977年 | 25篇 |
1976年 | 37篇 |
1975年 | 20篇 |
1974年 | 14篇 |
1972年 | 14篇 |
1966年 | 12篇 |
排序方式: 共有3794条查询结果,搜索用时 44 毫秒
101.
C. M. Franks F. StC. Golden I. F. G. Hampton M. J. Tipton 《European journal of applied physiology》1997,75(3):279-281
Many drowning victims have alcohol in their blood, but it is not clear whether there is a causal relationship. This study examined the effect of moderate alcohol consumption on the initial responses to cold water immersion. Sixteen subjects wearing swimming costumes undertook two, 3-min head-out seated immersions in water at 15??°C. One hour before immersion, subjects drank either 3.7?ml?·?kg body water–1 of 40% v:v alcohol as vodka, or an equivalent volume of water (control) mixed with squash. On immersion, the average blood alcohol concentration was 23?mmol?·?l–1 (105?mg?·?100?ml–1) after alcohol consumption and zero in the control condition. Respiratory frequency in the first 20?s of immersion was found to be reduced (P?0.05) by 10% (a total of 2–3 breaths) after alcohol consumption compared to the control immersion. Tidal volume, heart rate, rectal temperature and skin temperatures did not differ significantly between immersions. It is concluded that moderate alcohol consumption does not attenuate the initial "cold shock" responses to a practically significant extent and is thus unlikely to reduce the risk of drowning on immersion in cold water. 相似文献
102.
The bias favoring deletion over inversion in DH-JH rearrangement has been
known for years, but the underlying mechanism has yet to be fully defined.
It has been suggested that the ratio of deletion/inversion is determined by
the combined effect of two factors: (i) the relative strengths of 5' and 3'
recombination signal sequences (RSS) of a DH segment, and (ii) the
efficiency with which the deletional product (one joint) forms relative to
the inversional product (two joints). In this study, we analyzed for the
first time the effect of factor 1 alone on the biased 3' RSS utilization in
DH-JH joining by using deletional plasmids in an extrachromosomal substrate
V(D)J recombination assay. It was found that the 3' RSS and associated
coding end (12 bp) mediate recombination more efficiently than the 5'
RSS/coding end DH-JH plasmids. These results demonstrate that the effect of
the RSS/coding end alone can account, at least partially, for the
predominant deletion in DH-JH recombination. The potential effect of the
relative strength of RSS and associated coding end on the ordered
rearrangement of DH-JH followed by VH to DH-JH was also assessed. When
recombination frequencies of D-->J (3' DH to J3) were compared with
frequencies of V-- >D (VHPJ14 to 3' DH or VHOX2 to 3' DH), it was found
that V-->D joining was, if anything, more efficient than D-->J
joining. Therefore, if all three segments were accessible, RSS/coding end
effects would not contribute to the ordered rearrangement of the IgH locus.
相似文献
103.
104.
The neutrophil phagosome is one of the most hostile environments that bacteria must face and overcome if they are to succeed as pathogens. Targeting bacterial defense mechanisms should lead to new therapies that assist neutrophils to kill pathogens, but this has not yet come to fruition. One of the limiting factors in this effort has been our incomplete knowledge of the complex biochemistry that occurs within the rapidly changing environment of the phagosome. The same compartmentalization that protects host tissue also limits our ability to measure events within the phagosome. In this review, we highlight the limitations in our knowledge, and how the contribution of bacteria to the phagosomal environment is often ignored. There appears to be significant heterogeneity among phagosomes, and it is important to determine whether survivors have more efficient defenses or whether they are ingested into less threatening environments than other bacteria. As part of these efforts, we discuss how monitoring or recovering bacteria from phagosomes can provide insight into the conditions they have faced. We also encourage the use of unbiased screening approaches to identify bacterial genes that are essential for survival inside neutrophil phagosomes. 相似文献
105.
Jolanda MA Boer Jan Albert Kuivenhoven Edith JM Feskens Evert G Schouten Louis M Havekes Jacob C Seidell John JP Kastelein Daan Kromhout 《Clinical genetics》1999,56(2):158-163
We investigated interactions between a mutation (D9N) in the lipoprotein lipase (LPL) gene and physical activity, as well as other lifestyle factors, on lipid traits in a population-based sample of Dutch men and women (n = 379). We used questionnaire information to classify physical activity, alcohol consumption, and smoking habits, while overweight was defined as a body mass index (BMI) > 25 kg/m2. Non-fasting blood samples were used for the determination of lipid traits and the D9N genotype. Fifteen subjects (4%) carried the mutation. They presented with higher levels of total cholesterol, apolipoprotein (apo) B and triglycerides compared to non-carriers. While no interactions with overweight, alcohol consumption, and smoking were found, a strong interaction between the D9N mutation and physical activity became apparent. Physically inactive D9N carriers (n = 5) had considerably higher total cholesterol (+2 mmol/l, p < or = 0.0001) and apo B levels (+63 mg/dl, p < or = 0.0001) compared to non-carriers of this mutation, whereas their high-density lipoprotein (HDL)-cholesterol concentrations were lower (-0.22 mmol/l, p < 0.05). This was not the case for physically active D9N carriers (n = 10). In conclusion, a common variant of the LPL gene (D9N) adversely affects plasma lipid and lipoprotein profiles. However, the unfavorable consequences may be counteracted by physical activity. 相似文献
106.
JM Kanyamurwa S Wamala R Baryamutuma E Kabwama R Loewenson 《African health sciences》2013,13(3):829-841
Background
Globalization-related measures to liberalize trade and stimulate export production were applied in Uganda in the late 1980s, including in the coffee production sector, to revitalize agricultural production, increase incomes to farmers and improve rural food security.Objective
To explore the different effects of such measures on the health and dietary outcomes of female coffee and food small holder farmers in Uganda.Methods
We gathered evidence through a cross-sectional comparative interview survey of 190 female coffee producers and 191 female food producers in Ntungamo district. The study mostly employed quantitative methods of data collection, targeting the sampled households. We also utilized qualitative data; collected three months after the household survey data had been collected and their analysis had been accomplished. Using qualitative interviews based on an unstructured interview guide, extra qualitative information was collected from key informants at national, district and community levels. This was among other underlying principles to avoid relying on snapshot information earlier collected at household level in order to draw valid and compelling conclusions from the study. We used indicators of production, income, access to food and dietary patterns, women''s health and health care. Of the two groups selected from the same area, female coffee producers represented a higher level of integration into liberalised export markets.Results
Document review suggests that, although Uganda''s economy grew in the period, the household economic and social gains after the liberalization measures may have been less than expected. In the survey carried out, both food and coffee producers were similarly poor, involved in small-scale production, and of a similar age and education level. Coffee producers had greater land and livestock ownership, greater access to inputs and higher levels of income and used a wider variety of markets than food producers, but they had to work longer hours to obtain these economic returns, and spent more cash on health care and food from commercial sources. Their health outcomes were similar to those of the food producers, but with poorer dietary outcomes and greater food stress.Conclusions
The small-scale women farmers who are producing food cannot rely on the economic infrastructure to give them support for meaningful levels of production. However, despite having higher incomes than their food producing counterparts, the evidence showed that women who are producing coffee in Uganda as an export commodity cannot rely on the income from their crops to guarantee their health and nutritional wellbeing, and that the income advantage gained in coffee-producing households has not translated into consistently better health or food security outcomes. Both groups have limited levels of autonomy and control to address these problems. 相似文献107.
108.
109.
The patellofemoral joint was imaged with magnetic resonance (MR) in the axial plane while the knee was positioned from 0 degrees to 32 degrees of flexion (nine positions). These multiple sequential images obtained within the early phases of flexion of the knee were viewed in a "cine-loop" format, producing a kinematic study that clearly demonstrated the relationship of the patella to the trochlear groove. Four healthy subjects and one patient with known bilateral subluxing patellae were studied. The preliminary results suggest that kinematic MR imaging of the patellofemoral joint is potentially useful for the evaluation of patellar tracking abnormalities. 相似文献
110.
Pernes JM; Vitoux JF; Brenoit P; Raynaud A; Parola JL; Roth JP; Angel CY; Fiessinger JN; Roncato M; Gaux JC 《Radiology》1986,158(2):481-485
Thirty-five patients hospitalized for recent angiographically documented arterial occlusion in the legs (27 femoropopliteal arteries and eight grafts) benefited from local fibrinolytic therapy delivered at the site of the occlusion with a 4- or 5-F catheter. This therapy combined a continuous urokinase (UK) infusion of 1,000 U/kg/hour and a lysyl plasminogen (LYS-PLG) infusion of 15 microkatals every 30 minutes. Angiographically confirmed lysis was obtained in 85% of the cases. Only 3% of the patients had major and 6% had minor groin hematomas. Only two patients had concentrations of fibrinogen as low as 100 mg/dl. Intravascular infusion of UK-LYS-PLG is as effective as streptokinase. Its excellent tolerance makes it a good alternative in the treatment of acute ischemia in the lower limbs. 相似文献