全文获取类型
收费全文 | 7517篇 |
免费 | 638篇 |
国内免费 | 290篇 |
专业分类
电工技术 | 347篇 |
综合类 | 383篇 |
化学工业 | 1025篇 |
金属工艺 | 339篇 |
机械仪表 | 382篇 |
建筑科学 | 454篇 |
矿业工程 | 160篇 |
能源动力 | 193篇 |
轻工业 | 377篇 |
水利工程 | 117篇 |
石油天然气 | 243篇 |
武器工业 | 74篇 |
无线电 | 694篇 |
一般工业技术 | 689篇 |
冶金工业 | 2118篇 |
原子能技术 | 79篇 |
自动化技术 | 771篇 |
出版年
2024年 | 45篇 |
2023年 | 124篇 |
2022年 | 239篇 |
2021年 | 371篇 |
2020年 | 244篇 |
2019年 | 182篇 |
2018年 | 234篇 |
2017年 | 219篇 |
2016年 | 228篇 |
2015年 | 273篇 |
2014年 | 360篇 |
2013年 | 358篇 |
2012年 | 445篇 |
2011年 | 421篇 |
2010年 | 379篇 |
2009年 | 315篇 |
2008年 | 255篇 |
2007年 | 236篇 |
2006年 | 236篇 |
2005年 | 191篇 |
2004年 | 165篇 |
2003年 | 141篇 |
2002年 | 139篇 |
2001年 | 111篇 |
2000年 | 106篇 |
1999年 | 161篇 |
1998年 | 692篇 |
1997年 | 402篇 |
1996年 | 265篇 |
1995年 | 184篇 |
1994年 | 130篇 |
1993年 | 136篇 |
1992年 | 43篇 |
1991年 | 36篇 |
1990年 | 42篇 |
1989年 | 36篇 |
1988年 | 24篇 |
1987年 | 21篇 |
1986年 | 15篇 |
1985年 | 24篇 |
1984年 | 5篇 |
1982年 | 19篇 |
1981年 | 13篇 |
1980年 | 15篇 |
1979年 | 4篇 |
1978年 | 6篇 |
1977年 | 47篇 |
1976年 | 94篇 |
1975年 | 3篇 |
1973年 | 3篇 |
排序方式: 共有8445条查询结果,搜索用时 15 毫秒
51.
It seems obvious in retrospect that the treatment of disorders by interocclusal devices followed two paths: stabilization splints and functional orthopedic appliances. The dividing line between them is not always clear. Both have some function related to the position of the mandible. They may not differ significantly in their control of occlusal stability (e.g., telescoping devices anchored to stabilization splints). The stabilization splint, as well as other conservative measures, will play an increasing role in accepted therapy for TMD. The use of anterior repositioning devices for TMD, including MPD syndrome, will decrease. Research may provide answers that allow them to be used more specifically and predictably. Perhaps there will be but little change in their use where there is an association of TMD and Class II malocclusion. There will be an increase in the use of interocclusal devices for the treatment of snoring and obstructive apnea. Some additional directions seem to have emerged in the late 1980s and early 1990s: In the absence of pain and significant debilitation, treatment for TMD, if any, is to be reversible. Prevention or aggravation of TMD should be practiced to the extent possible during dental procedures. One long-term, well-designed, prospective study indicated that the incidence and severity of TMD could be reduced by appropriate occlusal adjustment. There is a small, but nevertheless important minority of patients with TMD who progress to persistent pain and/or dysfunction. Initial management of the vast majority of patents with TMD should be use of noninvasive reversible therapies. Surgery is indicated in only a relatively small percentage of cases of TMD. Research on interocclusal devices should not terminate simply because they are in part dental devices (i.e., biomechanical forms of treatment). The diagnosis and treatment of TMD has been called a dilemma, especially for those patients with chronic pain for whom no treatment has been effective. However, it would be ill-advised to abandon what treatment is already known to be effective by allowing those few but psychosocially important patients with chronic pain to determine what should be done for the vast majority of patients with TMD: reversible forms of treatment, including physiotherapy, pharmacologicals, and the stabilization occlusal bite plane splint. 相似文献
52.
SP Kraft 《Canadian Metallurgical Quarterly》1998,33(4):237-239
PURPOSE: The authors describe the first case of delayed antimetabolite-related corneal epithelial toxicity after trabeculectomy and its successful treatment with limbal stem cell transplantation. METHODS: A 73-year-old woman underwent trabeculectomy with intraoperative mitomycin C. After surgery she received six 5-mg injections of subconjunctival 5-fluorouracil (5-FU) adjacent to the bleb. RESULTS: The patient had a functioning trabeculectomy and clear cornea until 30 months after surgery, at which time she developed a nonhealing superior corneal epithelial defect. After 4 months of conservative medical management, an autologous limbal stem cell transplantation was performed. The epithelial defect resolved completely within 1 week of limbal stem cell transplantation. CONCLUSIONS: Delayed corneal epithelial toxicity may be a late complication of antimetabolite-augmented trabeculectomy. 相似文献
53.
PURPOSE: To determine the apical versus basolateral polarity of the putative anion exchanger in cultured bovine corneal endothelial cells (BCECs) and to examine the influence of Cl--dependent membrane potential (Em) changes on HCO3- transport. METHODS: BCECs grown on permeable supports were used for independent perfusion of apical and basolateral surfaces. Intracellular pH (pHi) was measured using the fluorescent dye BCECF. Relative changes in Em were measured using the fluorescent dye bis-oxonol. Western blot analysis was used to detect immunoreactivity against the anion exchanger (AE1 or AE2). RESULTS: Cl- removal from apical and basolateral surfaces produced cellular alkalinization (apical side, 0.07 pH units; basolateral side, 0.06 pH units; both sides, 0.20 pH units). Application of 100 microM H2-4,4'-diisothiocyanatodihydrostilbene-2,2'-disulfonic acid (DIDS), an anion exchange inhibitor, on the apical side produced an alkalinization (0.02 pH units) followed by acidification (-0.05 pH units), whereas basolateral H2DIDS caused a substantial acidification (-0.16 pH units). In the absence of Na+, Cl- removal from the apical side caused a transient alkalinization (0.03 pH units) followed by a return to baseline; Cl- removal from the basolateral side caused a small (-0.03) acidification. In Na+-free Ringer, apical H2DIDS produced a transient alkalinization (0.02 pH units), whereas basolateral exposure had no effect. 5-Nitro-2-(3-phenylpropylamino)benzoic acid (NPPB), N-phenylanthranilic acid (DPC), and niflumic acid (50-200 microM), known Cl- channel blockers, produced cellular acidification in control Ringer. Niflumic acid hyperpolarized Em and inhibited depolarization after Cl- removal. Western blot analysis failed to detect AE2 expression in cultured BCECs. However, fresh BCECs produced a trace response. CONCLUSIONS: Physiological activity of an apical anion exchanger is weak in cultured BCECs. Cultured BCECs have significant Cl- conductance. Thus, cellular alkalinization after Cl- removal is caused primarily by depolarization of Em, which drives HCO3- influx through the basolateral electrogenic Na+:nHCO3- cotransporter. In contrast with cultured BCECs, AE2 may be present in fresh cells. 相似文献
54.
Clinical experience suggests that the visual neglect in stroke patients fluctuates over short periods of time. This fluctuation has been variously attributed to fatigue, time of day, previous activities, patient learning and compensation. Such fluctuations have clinical implications for the assessment and rehabilitation of visual neglect but do date no formal study has evaluated the extent of such fluctuation over the course of a day. Twenty-two patients with an acute stroke and 19 patients with convalescent stroke were examined for visual neglect twice on the same day using the Visual Neglect Recovery Index (VNRI), a valid and sensitive measure of the severity of neglect, which could be used to select acute patients for trials of treatment of neglect. The inter-test reliability was extremely high. In contrast to past clinical accounts most patients failed to show significant fluctuation. Although preliminary, this finding suggests that a single assessment of visual neglect, using the VNRI, could help select patients for treatment trials. 相似文献
55.
56.
57.
58.
59.
Claudia Kuster Jean‐Charles Bazin Cengiz Öztireli Teng Deng Tobias Martin Tiberiu Popa Markus Gross 《Computer Graphics Forum》2014,33(2):1-10
Multi‐view reconstruction aims at computing the geometry of a scene observed by a set of cameras. Accurate 3D reconstruction of dynamic scenes is a key component for a large variety of applications, ranging from special effects to telepresence and medical imaging. In this paper we propose a method based on Moving Least Squares surfaces which robustly and efficiently reconstructs dynamic scenes captured by a calibrated set of hybrid color+depth cameras. Our reconstruction provides spatio‐temporal consistency and seamlessly fuses color and geometric information. We illustrate our approach on a variety of real sequences and demonstrate that it favorably compares to state‐of‐the‐art methods. 相似文献
60.
This paper investigates the cubature Kalman filtering (CKF) for nonlinear dynamic systems. This third‐degree rule based filter employs a spherical‐radial cubature rule to numerically compute the integrals encountered in nonlinear filtering problems, thereby removing the requirements of explicitly computing the Jacobians. The cubature rule, however, requires computing the intractable integrals over a high‐dimensional spherical region for multidimensional applications. Moreover, the cubature formula that has been used to construct the spherical cubature formula has some demerits, most notably its inconvenient properties in computation and low estimation accuracy. Aimed at these issues, a general class of CKFs that uses only cubature rules is derived in this paper. It can be shown that the conventional CKF is a special case of the proposed algorithm. The paper also includes higher‐degree CKFs, especially two representative types of the fifth‐degree CKFs. Performance of the proposed algorithms is demonstrated via two target tracking problems. The experimental results, presented herein, illustrate the superior performance of higher‐degree CKFs to conventional nonlinear filters. 相似文献