全文获取类型
收费全文 | 1066篇 |
免费 | 120篇 |
国内免费 | 59篇 |
专业分类
耳鼻咽喉 | 3篇 |
儿科学 | 44篇 |
妇产科学 | 22篇 |
基础医学 | 74篇 |
口腔科学 | 17篇 |
临床医学 | 177篇 |
内科学 | 277篇 |
皮肤病学 | 18篇 |
神经病学 | 128篇 |
特种医学 | 243篇 |
外科学 | 78篇 |
综合类 | 34篇 |
预防医学 | 51篇 |
眼科学 | 11篇 |
药学 | 38篇 |
中国医学 | 6篇 |
肿瘤学 | 24篇 |
出版年
2022年 | 5篇 |
2021年 | 10篇 |
2020年 | 6篇 |
2019年 | 5篇 |
2018年 | 16篇 |
2017年 | 6篇 |
2016年 | 3篇 |
2015年 | 14篇 |
2014年 | 18篇 |
2013年 | 35篇 |
2012年 | 32篇 |
2011年 | 27篇 |
2010年 | 31篇 |
2009年 | 30篇 |
2008年 | 28篇 |
2007年 | 61篇 |
2006年 | 25篇 |
2005年 | 26篇 |
2004年 | 23篇 |
2003年 | 20篇 |
2002年 | 17篇 |
2001年 | 20篇 |
2000年 | 11篇 |
1999年 | 19篇 |
1998年 | 56篇 |
1997年 | 35篇 |
1996年 | 65篇 |
1995年 | 49篇 |
1994年 | 47篇 |
1993年 | 52篇 |
1992年 | 22篇 |
1991年 | 18篇 |
1990年 | 38篇 |
1989年 | 37篇 |
1988年 | 41篇 |
1987年 | 45篇 |
1986年 | 32篇 |
1985年 | 35篇 |
1984年 | 24篇 |
1983年 | 22篇 |
1982年 | 16篇 |
1981年 | 27篇 |
1980年 | 23篇 |
1979年 | 8篇 |
1978年 | 11篇 |
1977年 | 17篇 |
1976年 | 8篇 |
1975年 | 11篇 |
1974年 | 5篇 |
1973年 | 3篇 |
排序方式: 共有1245条查询结果,搜索用时 15 毫秒
41.
Preparation, characterization, and performance of magnetic iron-carbon composite microparticles for chemotherapy 总被引:29,自引:0,他引:29
Magnetic microcarrier particles useful for delivering chemotherapeutic drug molecules are described. The particles are formed by joint deformation of iron and carbon in a ball mill. Physical, chemical, and functional characterization has been carried out on the particles. Physical characteristics include microscopy, particle size analysis (0.5-5 microm), surface area (250 m2/g), water vapor adsorption isotherm (hydrophobic surface), and analysis of the iron-carbon interface by M?ssbauer spectroscopy, X-ray diffraction, and differential thermal analysis. Chemical analysis was used to identify elements in the particles other than carbon and iron. Functional characteristics measured included the particles' ability to adsorb and desorb doxorubicin, cytotoxicity, and their magnetic susceptibility. 相似文献
42.
Ghosh D; Stewart DR; Nayak NR; Lasley BL; Overstreet JW; Hendrickx AG; Sengupta J 《Human reproduction (Oxford, England)》1997,12(5):914-920
The present study was undertaken to assess the temporal association between
the profiles of serum concentrations of oestradiol-17beta, progesterone,
chorionic gonadotrophin (CG) and relaxin in pregnancies established
naturally, and after embryo transfer, as well as in failed pregnancies in
rhesus monkeys. In naturally mated cycles (group 1) a conception rate of
75% was obtained. In group 1, the mean day of CG detection in serum was
11.5 +/- 1.9 day post-ovulation, and for relaxin, 9.0 +/- 2.5 day
post-ovulation. In group 2, embryo transfer to synchronous, non-mated
surrogate recipients was performed; seven embryo transfer cycles yielded
three pregnancies which were allowed to continue to term and normal infants
were delivered. In embryo transfer cycles the mean day of CG detection was
14.8 +/- 1.8 day post- ovulation, and for relaxin, 11.4 +/- 2.6 day
post-ovulation. A delay of about 3 days was observed in the appearance in
circulation of CG (P < 0.05) and also of relaxin (P < 0.05) between
natural mated and embryo transfer conception cycles. Significant
differences (P < 0.05 for progesterone and P < 0.03 for oestradiol)
were obtained for the areas under the curves for progesterone and
oestradiol between days 12 and 16 in conception cycles compared with failed
pregnancies. These data provide the first observation of the normal
hormonal signals associated with maternal recognition of transferred
embryos during the peri- implantation period, and suggest that the use of
such an experimental primate embryo transfer model may help to elucidate
components of maternal and embryonic signal-response mechanisms during
embryo implantation.
相似文献
43.
Identification of the multiple endocrine neoplasia type 1 (MEN1) gene. The European Consortium on MEN1 总被引:10,自引:0,他引:10
Lemmens I; Van de Ven WJ; Kas K; Zhang CX; Giraud S; Wautot V; Buisson N; De Witte K; Salandre J; Lenoir G; Pugeat M; Calender A; Parente F; Quincey D; Gaudray P; De Wit MJ; Lips CJ; Hoppener JW; Khodaei S; Grant AL; Weber G; Kytola S; Teh BT; Farnebo F; Thakker RV 《Human molecular genetics》1997,6(7):1177-1183
44.
Amelie Perron RN PhD Trudy Rudge RN RMHN PhD Dave Holmes RN PhD 《Nursing philosophy》2010,11(2):100-111
The concept of citizenship is becoming more and more prominent in specific fields, such as psychiatry/mental health, where it is constituted as a solution to the issues of exclusion, discrimination, and poverty often endured by the mentally ill. We argue that such discourse of citizenship represents a break in the history of psychiatry and constitutes a powerful strategy to counter the effects of equally powerful psychiatric labelling. However, we call into question the emancipatory promise of a citizenship agenda. Foucault's concept of governmentality is helpful in understanding the production of the citizen subject, its location within the ‘art of government’, as well as the ethical and political implications of citizenship in the context of mental health. 相似文献
45.
PB Greer K Dahl MA Ebert M White C Wratten P Ostwald P Pichler JW Denham 《Journal of Medical Imaging and Radiation Oncology》2008,52(5):517-524
The aims of this study were to investigate whether intrafraction prostate motion can affect the accuracy of online prostate positioning using implanted fiducial markers and to determine the effect of prostate rotations on the accuracy of the software‐predicted set‐up correction shifts. Eleven patients were treated with implanted prostate fiducial markers and online set‐up corrections. Orthogonal electronic portal images were acquired to determine couch shifts before treatment. Verification images were also acquired during treatment to assess whether intrafraction motion had occurred. A limitation of the online image registration software is that it does not allow for in‐plane prostate rotations (evident on lateral portal images) when aligning marker positions. The accuracy of couch shifts was assessed by repeating the registration measurements with separate software that incorporates full in‐plane prostate rotations. Additional treatment time required for online positioning was also measured. For the patient group, the overall postalignment systematic prostate errors were less than 1.5 mm (1 standard deviation) in all directions (range 0.2–3.9 mm). The random prostate errors ranged from 0.8 to 3.3 mm (1 standard deviation). One patient exhibited intrafraction prostate motion, resulting in a postalignment prostate set‐up error of more than 10 mm for one fraction. In 14 of 35 fractions, the postalignment prostate set‐up error was greater than 5 mm in the anterior–posterior direction for this patient. Maximum prostate rotations measured from the lateral images varied from 2° to 20° for the patients. The differences between set‐up shifts determined by the online software without in‐plane rotations to align markers, and with rotations applied, was less than 1 mm (root mean square), with a maximum difference of 4.1 mm. Intrafraction prostate motion was found to reduce the effectiveness of the online set‐up for one of the patients. A larger study is required to determine the magnitude of this problem for the patient population. The inability in the current software to incorporate in‐plane prostate rotations is a limitation that should not introduce large errors, provided that the treatment isocentre is positioned near the centre of the prostate. 相似文献
46.
47.
JW Gregory SA Greene RT Jung CM Scrimgeour MJ Rennie 《Archives of disease in childhood》1993,68(2):205-209
Fourteen children receiving one year of recombinant human growth hormone (rhGH) treatment underwent measurement of serial changes in body composition (measured by skinfold thickness, bioelectrical impedance, and H2(18)O dilution), resting energy expenditure (REE, estimated by ventilated hood indirect calorimetry), and total free living daily energy expenditure (TEE, measured by the doubly labelled water technique). Mean height velocity increased from 4.9 to 8.6 cm/year after six months of treatment. Fat free mass (FFM) increased more during the first six weeks (24.4 g/day) than from six to 26 weeks of treatment (6.8 g/day); fat mass decreased by 7.2 g/day and 1.1 g/day respectively. The six week increase in REE (kJ/day) was maintained after six months of treatment, though expressed per kilogram FFM (kJ/kgFFM/day), returned to pretreatment values by three months. Height velocity increases at six months correlated with six week changes in fat mass measured by skinfold thickness and REE, though use of this relationship to predict growth response in individuals is limited by the wide 95% prediction intervals. No significant changes in growth, body composition, or energy expenditure were observed between six and 12 months of treatment, in either patients who had initially responded well to treatment or those who were poor initial responders to treatment and who had their dose of rhGH doubled after six months. 相似文献
48.
Age-related postural deficits elicit compensatory mechanisms such as ankle dorsiflexion in the elderly. To gain further insight into this problem, the ability to match an ankle angle during quiet stance was studied in 12 elderly and 12 young subjects. Following an initial single limb angular perturbation presented in the ±4° range, a subject had to return a tilt platform to level, as determined by the nonperturbed limb. Elderly subjects exhibited significant positive (0.9°) over-shoot of the level position, in contrast to young subjects who matched ankle angle with a mean error of −0.1°. The elderly group also exhibited an increase in positioning error for angular displacements in the range between −1 and +1°. The results document age-related postural changes in ankle positioning which might affect postural stability in older adults. 相似文献
49.
50.
Injury-induced Regulation of Ciliary Neurotrophic Factor mRNA in the Adult Rat Brain 总被引:6,自引:0,他引:6
Nancy Y. Ip Stanley J. Wiegand Joanne Morse John S. Rudge 《The European journal of neuroscience》1993,5(1):25-33
Ciliary neurotrophic factor (CNTF) is a pleiotropic molecule that acts as a neurotrophic factor for a wide range of embryonic neurons as well as a differentiation factor for sympathetic neuroblasts and O2A progenitor cells in culture. CNTF messenger RNA (mRNA) is present at very low levels in the normal adult rat central nervous system (CNS), but is dramatically up-regulated after an aspiration lesion of dorsal hippocampus and overlying cortex, in the area coincident with glial scar. The increased level of CNTF mRNA in lesioned hippocampus is maximal by 3 days and is sustained for up to 20 days, the longest time point examined. In contrast, mRNA levels for brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3) were slightly decreased during the same period. In situ hybridization experiments revealed that cells expressing CNTF mRNA were concentrated at the margin of the wound, and also present within the gelfoam which filled the lesion cavity. This distribution of CNTF-expressing cells corresponded very closely to that of cells expressing high levels of glial fibrillary acidic protein mRNA at the wound site. Paralleling the observed increase in CNTF mRNA, increased levels of CNTF-like neurotrophic activity were apparent in soluble extracts of the lesioned tissues. This neurotrophic activity for ciliary ganglion neurons was completely blocked by the addition of neutralizing antiserum against CNTF. Basic fibroblast growth factor, which has been shown by others to increase after a similar lesion paradigm (Frautschy et al., Brain Res. , 553 , 291–299, 1991), does not contribute appreciably to this trophic activity. We conclude that CNTF is markedly increased as a function of injury to the CNS and that its expression is most likely restricted to reactive astrocytes in the glial scar. 相似文献