全文获取类型
收费全文 | 6614篇 |
免费 | 266篇 |
国内免费 | 25篇 |
专业分类
耳鼻咽喉 | 30篇 |
儿科学 | 115篇 |
妇产科学 | 57篇 |
基础医学 | 899篇 |
口腔科学 | 88篇 |
临床医学 | 391篇 |
内科学 | 1674篇 |
皮肤病学 | 102篇 |
神经病学 | 541篇 |
特种医学 | 289篇 |
外科学 | 1324篇 |
综合类 | 20篇 |
预防医学 | 239篇 |
眼科学 | 107篇 |
药学 | 345篇 |
中国医学 | 6篇 |
肿瘤学 | 678篇 |
出版年
2023年 | 45篇 |
2022年 | 85篇 |
2021年 | 152篇 |
2020年 | 89篇 |
2019年 | 112篇 |
2018年 | 135篇 |
2017年 | 112篇 |
2016年 | 138篇 |
2015年 | 137篇 |
2014年 | 193篇 |
2013年 | 245篇 |
2012年 | 401篇 |
2011年 | 435篇 |
2010年 | 220篇 |
2009年 | 190篇 |
2008年 | 363篇 |
2007年 | 417篇 |
2006年 | 411篇 |
2005年 | 423篇 |
2004年 | 391篇 |
2003年 | 407篇 |
2002年 | 354篇 |
2001年 | 82篇 |
2000年 | 66篇 |
1999年 | 84篇 |
1998年 | 96篇 |
1997年 | 95篇 |
1996年 | 86篇 |
1995年 | 83篇 |
1994年 | 65篇 |
1993年 | 64篇 |
1992年 | 64篇 |
1991年 | 50篇 |
1990年 | 62篇 |
1989年 | 51篇 |
1988年 | 45篇 |
1987年 | 46篇 |
1986年 | 33篇 |
1985年 | 27篇 |
1984年 | 33篇 |
1983年 | 33篇 |
1982年 | 35篇 |
1981年 | 17篇 |
1980年 | 26篇 |
1979年 | 15篇 |
1978年 | 17篇 |
1977年 | 15篇 |
1974年 | 24篇 |
1973年 | 14篇 |
1972年 | 15篇 |
排序方式: 共有6905条查询结果,搜索用时 15 毫秒
21.
22.
Akio Sakamoto Tatsuya Yoshida Hidetaka Yamamoto Yoshinao Oda Masazumi Tsuneyoshi Yukihide Iwamoto 《Journal of orthopaedic science》2007,12(4):361-365
Background Congenital pseudarthrosis of the tibia (CPT) is frequently, but not always, associated with neurofibromatosis type 1 (NF1).
Double inactivation of the NF1 gene has been reported to be the pathogenesis of CPT in NF1 cases.
Methods We analyzed the loss of heterozygosity (LOH) of the NF1 gene in cases of CPT with NF1 to examine whether double inactivation was seen in the case. In addition to morphological analysis,
immunoexpression of differentiation markers was examined.
Results and discussion The tibia tapered with the zone phenomenon from mature to immature bone with osteoblastic rimming, resembling osteofibrous
dysplasia. Osteosclerotic bowed bone with a small number of osteoclasts suggested dysfunction of bone remodeling. Fibrous
tissue at the site of pseudarthrosis was associated with the periosteum and demonstrated myofibroblastic differentiation accompanied
by massive cartilage formation, suggesting some misdirection during the differentiation of periosteum to myofibroblasts or
chondrocytes. LOH of the NF1 gene locus was not seen in fibrous tissue. This result suggests that CPT is not accompanied by double inactivation in every
NF1 case. 相似文献
23.
Abstract: In an experimental dog model of acute biventricular failure, the effects of left ventricular (LV) assist on renal hemodynamics and function were evaluated. After the induction of severe cardiac failure by multiple ligation of the coronary arteries, LV assist with a 40 ml pneumatic pulsatile pump was initiated, and the aortic flow was maintained at control values. The right atrial pressure (RAP) rose to 21.3 mm Hg with the appearance of profound right ventricular (RV) failure. Renal arterial blood flow (RAF) decreased to about 60% of the control value after 2 h of LV assist. The urine volume decreased and renal function deteriorated progressively. RV assist decreased the RAP to 4.8 mm Hg, and the reduced RAF recovered. After 3 h of RV assist, the RAF returned to initial values and the urine volume increased, but renal function did not recover. Advanced biventricular failure with elevated RAP during LV assist reduced renal perfusion and impaired renal function and may be an indication for early RV assist 相似文献
24.
Masami Hamaguchi Takaharu Ishibashi Naoki Katsumata Akio Mitomi Shoichi Imai 《Cardiovascular drugs and therapy / sponsored by the International Society of Cardiovascular Pharmacotherapy》1992,6(6):611-622
Summary In beagle dogs anesthetized with enfluranenitrous oxide, effects of sodium nitroprusside (SNP; MR7S1) and nitroglycerin (NTG) on hemodynamics and main organ circulation were studied to evaluate their effectiveness and safety as hypotensive agents during anesthesia. SNP (MR7S1) infusion (1–10 g/kg/min) decreased arterial blood pressure in a dose-dependent manner. The hypotension was stable during the infusion. After discontinuation of infusion, the blood pressure rapidly returned to the initial level. The hypotension was associated with decreases in cardiac output and total peripheral resistance. NTG infusion (3–10 g/kg/min) decreased arterial blood pressure, too, but the hypotension was less marked and not dose dependent, and the recovery was slower. Neither drug changed the heart rate. Infusion of SNP (MR7S1) and NTG did not change the hypotension induced by the injection of adenosine, SNP, and NTG. Furthermore, cerebral blood flow, cerebral oxygen consumption, and renal blood flow were unchanged during the hypotension produced by either drug. Coronary blood flow was decreased, but this was due to decreases in cardiac oxygen consumption. In conclusion, SNP (MR7S1) is superior to NTG as a hypotensive agent during anesthesia in efficacy, clear dose dependency, and rapid recovery. The hypotension induced by NTG as well as SNP (MR7S1) seems to have no undesirable effects on the circulation of important organs. 相似文献
25.
Effects of different inspiratory concentrations of sevoflurane (fluorometyl-1,1,1,3,3,3,-hexafluoro-2-propylether) on blood pressure, heart rate and efferent activities of cardiac sympathetic, cardiac parasympathetic and renal sympathetic nerves were examined using rats either under the resting condition or during noxious mechanical stimulation of a hindpaw. Under the resting condition, an increase in the inspiratory concentration of sevoflurane from 2.1% to 4.2% gradually caused a decrease in blood pressure and heart rate. With the increase in the sevoflurane concentration, cardiac sympathetic nerve activity decreased, whereas renal sympathetic nerve and cardiac parasympathetic nerve activities did not change significantly. When noxious mechanical stimulation was applied to a hind-paw by pinching, blood pressure and heart rate, renal sympathetic and cardiac sympathetic nerve activities all increased at the 2.1% concentration of sevoflurane. The responses of these parameters were attenuated at the 3.1% concentration of sevoflurane and almost disappeared at the 4.2% concentration. Cardiac parasympathetic nerve activity did not change significantly during the pinching stimulation throughout the 2.1–4.2% concentration increase.(Kurosawa M, Meguro K, Nagayama T et al.: Effects of sevoflurane on autonomic nerve activities controlling cardiovascular functions in rats. J Anesth 3: 109–117, 1989) 相似文献
26.
27.
28.
29.
Technical quality evaluation of EEG recording based on electroencephalographers' knowledge 总被引:2,自引:0,他引:2
The aim of this study is to develop a technical quality evaluation system of electroencephalogram (EEG) recording in order to acquire technically satisfactory EEG records, which may contribute to the accuracy improvement of EEG interpretation. In our developed system, the evaluation of EEG recording comprises the detection of technical artifacts and physiological status, which indicates the recording status objectively. In addition, the caution signals to users are generated in the system according to the undesired status detected. The information displayed to users includes the updated EEG records and instant evaluation results. Two examples of evaluation results are introduced in this paper, illustrating unsatisfactory records and artifact free records, respectively. The experimental results are proposed to verify the effectiveness of the technical quality evaluation of EEG recording. The implementation of the technical quality evaluation of EEG recording is helpful to acquire technically satisfactory EEG records, which may improve the accuracy of results in both the visual and the automatic EEG interpretation, and ease the laborious work of EEG technicians in the recording progress. 相似文献
30.
Protective Role of Nitric Oxide in Staphylococcus aureus Infection in Mice 总被引:6,自引:0,他引:6 下载免费PDF全文
Sanae Sasaki Tomisato Miura Shinsuke Nishikawa Kyogo Yamada Mayuko Hirasue Akio Nakane 《Infection and immunity》1998,66(3):1017-1022
This study was carried out to determine the role of nitric oxide (NO) in Staphylococcus aureus infection in mice. NO production in spleen cell cultures was induced by heat-killed S. aureus. Expression of mRNA of the inducible isoform of NO synthase (iNOS) was induced in the spleens and kidneys of S. aureus-infected mice. When mice were treated with monoclonal antibodies (MAbs) against tumor necrosis factor alpha (TNF-α) or gamma interferon (IFN-γ) before S. aureus infection, the induction of iNOS mRNA expression in the kidneys was inhibited. These MAbs also inhibited NO production in spleen cell cultures stimulated with heat-killed S. aureus. NO production in the spleen cell cultures and levels of urinary nitrate plus nitrite were suppressed by treatment with aminoguanidine (AG), a selective inhibitor of iNOS. The survival rates of AG-treated mice were significantly decreased by either lethal or sublethal S. aureus infections. However, an effect of AG administration on bacterial growth was not observed in the spleens and kidneys of mice during either type of infection. Production of TNF-α and IFN-γ was not affected by AG treatment in vitro and in vivo. These results suggest that NO plays an important role in protection from lethality by the infection, but the protective role of NO in host resistance against S. aureus infection was not proved. Moreover, our results show that TNF-α and IFN-γ regulate NO production while NO may not be involved in the regulation of the production of these cytokines during S. aureus infection. 相似文献